Are the oceans rising or the continents going down? How can we know? The century old sustained rising of oceans, at a rate of 2-4 mm/y, remains a unexplained phenomenon; there is no correlation with temperature variations, so it is not due to the thermal variation of the volume of the oceans or to a decrease of Antarctic ice (which in fact is increasing).

A possibility, given that this raise of the oceans is not absolute but relative to coast, is that it is not the oceans’ absolute level that is raising but the continents that are sinking. A possible cause is global oscillations of the mantle surface level, and tectonic plates move up and down besides drifting.  Another cause is the solidification of the mantle under continental plates due to the decrease of Earth internal temperature. What do you think? Are the oceans rising or the continents going down (in average)? Only satellite measurements can solve the riddle?

To the best of our knowledge, sea-level is rising because the volume of water is increasing.

There is substantial local variation in sea-level change; it's falling in some parts of Canada. But of the dozens of controls on local and global sea-level, the net effect is currently an average global rise of about 3 mm/y. It's not really 'a riddle'. The phenomenon is well documented and there isn't too much mystery about the various causes. One could certainly debate their relative contributions.

Satellites already contribute much of the data that reveals the sea-level rise (and the relative stasis of the continents), and that substantiates some of the causes. For example, the TOPEX and Jason-2 satellites, constrained by gauges on earth, are important sources of data.

Two prominent causes of sea-level rise are thermal expansion and ice loss (for example in Greenland), but there are lots of others. Tectonic plates do definitely move up and down — it's an important phenomenon in geology and geomorphology, and it does affect sea-level in all sorts of ways (see that link).


How is the radiative efficiency of a given gas (like a given CFC) analytically calculated? E.g. the gases listed at http://www.ipcc.ch/publications_and_data/ar4/wg1/en/tssts-2-5.html . Do they calculate them analytically or theoretically?

Radiative efficiency is the radiative forcing per unit change in halocarbon mixing ratio.  Radiative Efficiency assumes that the Radiative Forcing is linear in mixing ratio—this is normally appropriate in the case of small perturbations in mixing ratio about current concentrations and is also appropriate for CFCs.  To calculate it requires a radiative transfer model, which includes both analytical and theoretical contributions.

The diagram shown in Hodnebrog et al.: "Global warming potentials and radiative efficiencies of halocarbons and related compounds: A comprehensive review" in Reviews of Geophysics
( http://dx.doi.org/10.1002/rog.20013 ) explains how radiative efficiency is calculated and is pasted below:


Is lower tropospheric temperature relevant to measure global warming? So according to this,

Global temperature update

Last month, the lower tropospheric temperature dropped 0.28 $\sf^\circ$C from February to March, which seems like a huge drop even if it's due to seasonal reasons.

A former NASA employee in that link conjectures it's not related to Coronavirus reduced CO2 emissions, but it might be related to Coronavirus reduced jet contrails.

My question is, is lower tropospheric temperature relevant to measuring global warming? Is there a relationship between lower tropospheric temperature and land-ocean level temperature, that seems to be the temperature we care about when measuring the impact on life on the planet?

Last month, the lower tropospheric temperature dropped 0.28°C from February to March, which seems like a huge drop even if it's due to seasonal reasons.

That is not what the linked article says. It instead says that the monthly lower tropospheric temperature UAH anomaly dropped by 0.28°C from February to March. The monthly temperature anomaly is the difference between the worldwide average temperature for that month in some year and the worldwide average temperature for that month over a baseline set of years, 1981 to 2010 in the case of the UAH temperature anomaly.

Seasonal temperature variations tend to be much stronger over land than over ocean. The other is that the Northern Hemisphere contains significantly more land than does the Southern Hemisphere. The combination of these two effects make worldwide temperatures exhibit a seasonal variation that reflects seasons in the Northern Hemisphere. February to March marks the transition from meteorological winter to meteorological spring (which starts on March 1 rather than March 22). One would expect March to be warmer than February, worldwide.

This is exactly what the GISTEMP records show:

source: https://data.giss.nasa.gov/gistemp/graphs_v4

Two key things can be extracted from the above graph: (1) There has been a general trend of warming since 1880, and (2) March 2020 was warmer than February 2020. What about monthly temperature anomalies, which is one of the topics in the question? The graph below portrays monthly GISTEMP temperature anomalies for recent years:

source: Same as above

The key relevant features from the above graphs is that while the monthly GISTEMP temperature for March 2020 was 0.62°C higher than that for February 2020, the monthly GISTEMP temperature anomaly for March 2020 was 0.06°C lower than that for February 2020.

Thus GISTEMP, which is based on temperature measurements near the surface, may have seen a muted version of the effect observed in the UAH data, which are based on satellite observations. I used "may have" because the 0.06°C drop seen by the GISTEMP model is barely above the 0.05°C uncertainty claimed for that model. The UAH model claims the same uncertainty (0.05°C), so their reported 0.28°C drop was apparently real.

  My question is, is lower tropospheric temperature relevant to measuring global warming?

The graph below compares surface-based measures (MET office, NASA, and NOAA) with satellite-based estimates (RSS and UAH). The MET office data starts in 1850 while the satellite data (UAH and RSS) don't start until 1981.

source: https://www.carbonbrief.org/explainer-how-surface-and-satellite-temperature-records-compare

All five datasets see the same general picture, which is temperatures generally rising, but with noisy peaks and troughs. Sometimes the satellite-based observations show variations that are not seen in the surface-based measurements, and other times it's the other way around. But in general, both see warming.

The satellites do not carry tethered thermometers that measure temperature at various heights in the atmosphere. They instead measure the intensities of electromagnetic radiation at various frequencies. The frequencies of interest for the UAH and RSS models are those at which the atmosphere is opaque.

There are issues with this approach. Excessive cloudiness (or the lack of clouds) can confuse the algorithms used to translate observations to temperatures. The instruments that measure the data degrade, and degrade unequally. To counteract this latter effect, radiosondes that do measure temperature are regularly launched to coincide with satellite passes so that the satellite instruments and algorithms can be recalibrated. Finally, while the satellite data do show a recent sharp climb (recent meaning the last six years or so), it's not nearly as steep as the increase observed near the surface by weather stations that actually do use thermometers.


How Fast Could a Cyclone at the North Pole Achieve? Given a tropical arctic region on a planet like our own, how fast could a cyclone go at the north pole where the Coriolis effect is greatest? In essence: have current cyclones maxed out the wind speeds or is there room to grow at the north pole?

There's a few problems with this question.  The first is, the Coriolis effect isn't a force in and of itself.  It's a velocity dependent effect.   If the wind speed is zero over the North or South Pole, the Coriolis effect would be zero.    If the wind speed is 100 kph over the pole, the Coriolis force would be (if this site is trustworthy) $0.000146 \times V \times \sin(latitude)$, in other words, pretty small, but over long distances, a small force can create a significant change in direction.   But there-in lies the problem to answering your question.   It would depend on the size of the cyclone and the initial wind speed of the cyclone.

The other problem is, the Coriolis force doesn't form neat little circles.  Around the polls it's more like this, so estimating a presumably circular cycolone entirely due to Coriolis is doubly problematic, because a cyclone wouldn't form.  You'd get some wind direction change but not a cyclone.

The cyclone effect is the most efficient way to move air, as lower mass warm air wants to rise to higher altitudes and higher mass cold air wants to fall to lower altitudes.  The cyclone may be initiated by the Coriolis effect but once begun, it's driven by warm water, evaporation, and variation in air mass.  If you notice, Cyclones lose strength both on land and if they turn north over the ocean.  The colder ocean reduces the wind strength because it evaporates less easily and the air over the ocean cools, so with real cyclones, as the Coriolis effect grows stronger as the cyclone moves north, the cyclone grows weaker.  Cyclones don't represent the Coriolis effect.  It only plays a role in getting them started.

As you probably know, the Coriolis effect doesn't actually move anything.  Objects move by their momentum and the Earth rotates by it's momentum and it's the earth that moves under the object that gives the impression of a Coriolis effect.   If you stand on the North Pole, the Earth rotates about about 1/2 the speed of the hour hand on your watch.   It's hard to imagine that has much effect on anything and it doesn't unless the distance is significantly large.

I can't do the precise math on this one, though I find it quite interesting, but the above is a general answer.   If you try the physics board, you might get a more mathematical answer, but I think the question might work better with a bowling ball and a friction-less earth rather than the wind and the earth and a cyclone of unspecified size.   I got curious, so I asked the question with that in mind.


With respect to latitude and time of year, what geopotential heights are associated with low pressure systems on the North American landmass? I was reading the paper The Washington DC tornado of 24 september 2001: pre-storm environment and radar perspectives which had this passage:

  At 1200 UTC 24 September 2001, at 500 hPa a deep (560 [gpdm]) cut-off extratropical low (midlatitude cyclone that is cut off from the jet stream) was located over Wisconsin with a central core temperature of -20 C." ().

Is 560 dm deep for that part of the country and that time of year?

I have revised the question based on suggestions fomr the comments.

Great question!
First, let's look at typical data: here are the 1981-2010 Reanalysis mean and standard deviation:

So looks like the mean 500 height in September for Wisconsin ranges from about 571-580 Dm, with a standard deviation of 36-42 Dm.  These are mean pressures, not lows or highs, so already, not that far off your low.  If (a big if) meteorological statistics are normally distributed, using this calculator, this would suggest a 560 Dm height would be in about the 29th-40th percentile, depending upon location.  A little lower than usual, but apparently fairly typical.

And just for good measure, looking back at the University of Wyoming, I was able to fairly quickly come upon:

A 554 or 555 Dm low.  If you want to look for more images (perhaps even the event you are reading about), you could also look in the Pix directory for the dates of interest at Iowa State's MTArchive.

But it appears that 560 Dm would be a fairly typical height for a low/trough during early fall.  Some people might still call it deep (30 Dm of contours on that plot from September would be fair), but it's nothing too abnormal.


Is this 70km crack in an ice shelf of Antarctica remarkable, or a regular occurrence? I've just seen the LiveScience article 70-Mile-Long Crack Opens Up in Anatarctica. I'm not sure if the title is a bit sensational or not, the crack is in an ice shelf, not the continent of Antarctica.

An ominous crack in an Antarctic ice shelf as wide as a football field is long takes on an otherworldly beauty in a new aerial image.
Snapped by scientists on NASA's IceBridge mission, the shot shows a rift in Larsen C, an ice shelf that is floating off the Antarctic Peninsula. When the crack eventually spreads across the entire ice shelf, it will create an iceberg the size of the state of Delaware, according to IceBridge. That's around 2,491 square miles (6,451 square kilometers).
As of Nov. 10, when the IceBridge scientists observed this crack, it was 70 miles (112 km) long and more than 300 feet (91 meters) wide. The dark depths of the crack plunge down about a third of a mile (0.5 km), all the way through the ice to the ocean below.
[...] Larsen C is Antarctica's fourth-largest ice shelf, and it holds back the land-based glaciers just behind it: Once the ice shelf goes, those slow-flowing glaciers have one less barrier in their journey toward the sea.

My primary question: is this a remarkable event, or something that over time happens regularly? Isn't this just a natural part of "those slow-flowing glaciers... journey toward the sea." ?
I'm also wondering 1) Is an iceberg the size of Delaware actually remarkable, or something that just happens from time-to-time? And 2) how they (actually) know the crack goes all the way to the ocean - can they actually see the water in images, or is this a hypothesis based on understanding of cracks of this length and width? I can ask as a separate questions if it's too much to ask here.

above: Image from here. "A huge crack can be seen in the Antarctic Peninsula's Larsen C ice shelf in this aerial image snapped on Nov. 10, 2016, as part of NASA's IceBridge mission. Credit: NASA/John Sonntag"

update:
The rift continues to be tracked. If I understand correctly, it is now over 350 meters wide and growing:

above: From A growing rift on Larsen C at the Project MIDAS website.
More can be read about NASA's operation Ice Bridge program at its official website. These are a series of areal flights over antarctic regionss to collect images and data. The image above of the crack in the Larsen-C ice shelf was a featured photo and more can be read about it here. In the image gallery the caption states:

Rift in Antarctica's Larsen C Ice Shelf
On Nov. 10, 2016, scientists on NASA's IceBridge mission photographed an oblique view of a massive rift in the Antarctic Peninsula's Larsen C ice shelf. Icebridge, an airborne survey of polar ice, completed an eighth consecutive Antarctic deployment on Nov. 18.

The photo was also featured in @NASA_ICE.
A short video explaining the mission and showing details of the aircraft's science equipment can be seen below (and is linked here):
https://www.youtube.com/watch?v=v3yMHHzLTCc

Is an iceberg the size of Delaware [6,451 square kilometers] actually remarkable, or something that just happens from time-to-time?

In March 2000 iceberg B-15 formed which was 11,000 sq. km. and 295 km long.
In October 1998 iceberg A-38 formed which was 6,900 sq. km.
A Delaware size iceberg would be the 3rd largest in the past 20 years.
The 1990 article The calving and drift of iceberg B-9 in the Ross Sea, Antarctica Antarctic Science Vol. 2 , pages 243-257 says:

The largest iceberg in recent times
(95 km x 95 km) calved from the Larsen Ice Shelf in early 1986

So a 9000 sq. km. iceberg broke off in 1986.
Contribution of giant icebergs to the Southern Ocean freshwater flux says:

an iceberg of 10,000 km2 in area broke from the Amery ice shelf in 1964

According to Antarctica shed a 208-mile-long berg in 1956:

A record iceberg seen in Antarctic
Little America V, Antarctica, Nov. 17- The U.S.S. Glacier, the Navy's most powerful icebreaker, has sighted an iceberg more than twice the size of Connecticut.
The berg was sighted by the Glacier early this week about 150 miles west of Scott Island. The ship reported it was 60 miles wide and 208 miles long- or more than 12,000 square miles, as against Connecticut's 5,009.

So 12,000 sq. mi. or 31,000 sq. km. is the largest known iceberg.
Both of the two previous references also mention a 1927 Antarctic iceberg that was 170 km long, but area is not given.  American Practical Navigator, says the 1927 iceberg was 100 mile long and 100 miles wide, so 25,000 sq. km.
In summary, an iceberg the size of that contemplated in the OP can be expected on the once every 5-20 years time scale.
update 7/12/2017:
according to the MIDAS project:

The calving occurred sometime between Monday 10th July and Wednesday 12th July 2017, when a 5,800 square km section of Larsen C finally broke away. The iceberg, which is likely to be named A68


Does negative reference evapotranspiration make sense using FAO Penman-Monteith equation? I computed the daily reference evapotranspiration $ET_0$ using the Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56. The outputs seems realistic regarding the dynamic and the annual total but the time series contains negative values (about 1% of the time series).

The computation involves many equations for the sub-terms but the general formula is the following:

$$
ET_0 = \frac{0.408 \Delta (R_n - G) + \gamma \frac{900}{T + 273}U_2(e_s - e_a)}{\Delta + \gamma(1+0.34 U_2)}
$$

with

$ET_0$ reference evapotranspiration [mm day-1],
$R_n$ net radiation at the crop surface [MJ m-2 day-1],
$G$ soil heat flux density [MJ m-2 day-1] (=0 in this case),
$T$ mean daily air temperature at 2 m height [°C],
$U_2$ wind speed at 2 m height [m s-1],
$e_s$ saturation vapour pressure [kPa],
$e_a$ actual vapour pressure [kPa],
$e_s - e_a$ saturation vapour pressure deficit [kPa],
$\Delta$ slope vapour pressure curve [kPa °C-1],
$\gamma$ psychrometric constant [kPa °C-1].

It appears that the negative values are due to a negative values of the net radiation $R_n$. A negative value of $R_n$ makes sense but what about negative $ET_0$ ? How should I deal with these as I intend to use $ET_0$ as input for hydrological modelling ?

Short answer, especially if it is about 1% of the time series and these values are just slightly negative, this likely indicates that the ET needs to be recalibrated slightly, and for practical purposes you can set the ET on those days to 0 mm/d. The ET calculations typically calculate potential ET, meaning that if there is no water available no ET will occur, and a similar concept applies to negative ET values (i.e. no demand for water -> no ET).

A couple of notes
- the reference $ET_0$ calculations were meant for ten-day or monthly time steps, not daily, which may be a reason for these results (see top of Ch 2)
- the equation seems to be for a specific type of reference grass, and they suggest adjusting the $ET_0$ based on crop type using a ratio; another potential adjustment to make

Overall if the negative values are infrequent and close to zero then likely setting to zero is not an issue, if the values are much less than zero than check the calculations and try the suggestions above to recalibrate the calculation.


How straight is the Kola superdeep borehole? The legendary Kola superdeep borehole is about 12 km deep. To achieve such depth, a major difficulty is to make sure the borehole is vertical straight.

Intuitively, when the borehole is deep enough, it is very hard to make sure that the drilling bit is still moving downwards.  Suppose it hits some hard rock, it can be easily deflected.

So, how straight is the Kola borehole? What technique is invoked in drilling straight downwards?

Borehole drifted from straight vertical by ~840 meters over 12,000 meters.  All drill-bore wander side to side some and Kola borehole did not drift much until depth exceeded 5000 meters.

See page 102 in the linked document.

Typical rotatory drill heads designed for vertical drilling can be steer to a small degree by using a simple concept: point the bit in the direction that one wants to drill. A common way to achieve this is by the use of a bend near the bit in a down hole steerable mud motor. the bend points the bit in a direction different from the axis of the well bore.

By spinning the drill head at a different rate vs the drill stem, allows the bit to drill in the direction it points.

Reference: PDF document gives an excellent technical summary of the project.


How abundant is high purity silica? Silicon is often touted as the second most abundant element in the Earth's crust. However, this can be misleading when looking at the abundance of high purity silica needed for manufacturing semiconductor wafers.
What purity level is required in naturally occurring silica in order to be used for manufacturing semiconductors? How abundant is it in the earth's crust?

Quoting from this paper: Haus R., Prinz S., Priess C. (2012) Assessment of High Purity Quartz Resources. In: Götze J., Möckel R. (eds) Quartz: Deposits, Mineralogy and Analytics. Springer Geology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-22161-3_2

What purity level is required in naturally occurring silica in order to be used for manufacturing semiconductors?

As high as possible.

...high purity quartz with total impurity levels less than 20 ppm...

20 ppm means that the silica has to be 99.998% pure. It is extremely hard to find silica that pure in nature.
More specifically:

Specific requirements as to tolerable limiting values differ from
industry to industry. In the lamp tubing and optics industries
aluminium content in the refined quartz concentrate should not exceed
20 ppm, other metals should be less than 1 ppm, and total impurities
less than 30 ppm. For semiconductor base materials and crucibles
aluminium content should be even lower, specified to less than 10 ppm,
other metals less than 0.1 ppm, and total impurities not to exceed 15
ppm.
Feedstock for solar silicon used in the photovoltaic industry should
generally have boron and phosphorus contents in the sub-ppm range
since these elements are most difficult to remove and negatively
affect the performance of the solar cells (Geerligs et al. 2002).
For microelectronics applications, e.g. in epoxy moulding compounds,
uranium and thorium, both responsible for soft errors by alpha
radiation, should be less than 2 ppb, and in low alpha applications,
even less than 0.5 ppb.


Is Australia the largest island? I had participated in a quiz recently and one of the questions was 'which is the largest island in the world?'. I wrote Australia as the answer remembering that it was the 5th largest country in the world and none of the top 4 were islands.

However (and rather dreadfully) the answer given was Greenland.I took this up with the committee providing the solutions, but they simply said that Australia isn't an island and is a continental mass?

I googled it and found the same argument online which seemed to confirm that Greenland was the largest island.

But Australia is a country and the collection of islands which is a continent (more accurately described as Oceania ) is sometimes called Australia. Neither of these names would still change the fact that Australia (the country) being an island is the largest island in the world! Can someone please clarify this for me?

Australia does get widely referred to as an island as well as as a continent - an island-continent sometimes. My understanding is that "continent" in terms of geology refers to the largest land mass of a continental plate and is more a matter of convention - a general agreement - than precise definition. Such definitions have been subject to revision.

This definition would have come after continental plates and plate tectonics were confirmed and widely accepted; proposed first by Alfred Wegener in 1912, acceptance did not come until the 1950's and 60's. Naming Australia an island predated this definition and still persists in popular usage but using the current definition it is a continent.

Greenland, being a part of the North American Plate but not it's largest landmass, gets defined as an island and is now considered the world's largest island.


What factors affect daily temperature range? I was wondering if the difference between the low temp and the high temp depended on just the humidity content and the altitude of a place. Or are there more factors? What about the time of year? How would the time of year affect diurnal temp variation if it does affect the range?

There are a lot of aspects affecting daily temperature. I want to distinguish between factors, which may change from day to day and others which are fixed and thus affect more the annual cycle of temperature (like altitude of place).

Some factors which affect daily temperature and change daily:

prevailing winds (temperature/moisture advection)
cloudiness
day of the year: duration of day (and thus insolation) is important for daily temperature range. The longer sun shines, the more solar radiation is absorbed by surface and the higher temperatures you get. For example, during equinox (march and september) day and night have the same duration and you have the longest or shortest day during solstice (in June and December). Thus this aspect is more relevant at middle and high latitudes.

Other aspects which do not change daily:

local relief and surface type (atmosphere is heated due to absorption of solar radiation by surface)
distance to ocean/large lake (maritime vs. continental climate)
latitude: the angle of incidence of solar radiation changes with latitude (and day of the year)


Glossary of oil and gas industry geophysical terms Reviewing market regulatory standards I came across the problem of finding a source that I could cite of concise, worldwide accepted industry geophysical terms.

So far I know Schlumberger Oilfield Glossary, SEG Wiki, SPE PetroWiki that give some information on some terms. In practice I need something like this definition in SEG Wiki for seismic crooked lines. Although in this case I don't think the term is well defined.

I am looking for a worldwide industry accepted glossary that I could rely on and cite. The broader it is the best will be for having less problems in future. Where would be the best place to find such source of information? Any other suggestions will be welcome.

Sheriff's Encyclopedic Dictionary is the closest thing to a canonical text, but the Schlumberger glossary is more up to date.

Sheriff is a scientific text, whereas the Schlumberger glossary is a little more generally accessible, but neither is comprehensive. Sheriff is especially poor on recent advances. On the plus side, you can edit it, if you're an SEG member.

After those two, Wikipedia is probably your next best bet.


What is real impact of Precision Agriculture? I am just wondering what is the real impact of Precision agriculture. I came across Airbus Intelligence and their Earth Observation services (Agriculture, forestry, environment) - It seems nice and attractive - however What is the real impact of using it?

PS: You can link me even French articles or topics (I am curious about French agriculture)

Thanks!

This is a placeholder answer in anticipation of (1) the question being closed before I can write a valid answer, and (2) I will replace this placeholder with a valid answer.

I have now partially filled in the placeholder, but what I wrote obviously still needs references.

The hope is that precision agriculture will be the basis for the next Green Revolution. The first Green Revolution started in the late 1950s and picked up steam during the 1960s. These techniques, now 50 to 60 years old, drastically changed farming in many developing countries, and even turned some of those countries from net food importers to net food exporters. The gains from those now dated techniques have plateaued in many places as of late; in some places productivity has even begun declining.

The goals of precision agriculture are to integrate many aspects of the earth and agricultural sciences with late 20th / early 21st century technology (modern direct sensing, remote sensing, internet of things, big data, ...)  so as to identify on a very precise scale exactly which land areas are in need of enhanced irrigation, fertilization, insecticides, herbicides, etc., -- and which areas are just fine as-is. The hopes are that this will reduce the overall need for irrigation, etc., thereby reducing stress on the land, and that this will be largely automated, thereby reducing the workload on farm workers.

These are the aims and hopes. The concepts do appear to be working in highly developed areas. But whether they can work well in the developing world is a bit suspect, let alone whether they can work at all in undeveloped areas of the world.

The bigger problem is that many estimates indicate the Earth's human population will increase by almost thirty per cent in just thirty years (from a bit over 7.5 billion to almost 10 billion) -- and that increase will be happening while the first Green Revolution is plateauing / declining. Something has to be done lest many parts of the world fall into famine. Precision agriculture might be one way address this bigger problem. Or it might not.


Is there such a thing as a "basalt dike"? I've always understood that basalt is an extrusive rock (formed by eruption), and dikes are intrusions (no eruption), so I would have thought that a dike could not be composed of basalt rock.

It's come to my attention that many people talk about "basalt dikes" in geology, and many websites, including pages of university geology departments, talk about dikes that are basalt.

The concept of a "basaltic dike" (note the "ic") makes sense to me: a gabbro or diabase dike whose parental magma had a basaltic composition.

So, I know that basaltic dikes exist, but I'd like to have confirmation that there is no such thing as a dike which is basalt rock.

"Basalt" per definition is a fine grained rock (that is, you can't see the individual crystals with the naked eye, aka aphanitic) with a certain chemical composition. The coarse grained form of this rock is called a "gabbro". A diabase (or dolerite) is something in between, but let's ignore it for the meanwhile for the sake of simplicity.

So quoting from your question:

  I've always understood that basalt is an extrusive rock (formed by
  eruption), and dikes are intrusions (no eruption)

This is not entirely accurate. Assuming that we are talking about rocks of this specific composition, then every extrusive rock is a basalt but not every intrusive rock is a gabbro (or diabase). Fine grained rocks, and basalts in our case, can also form in hypabyssal settings (underground, for example dykes) if conditions are favourable for very quick nucleation. When a magma of 1100 °C intrudes a 20 °C surface or 100 °C rocks several hundred metres deep, the cooling rate is not too different, causing similar fine grained textures in the rock.

The concept of "basaltic" may differ in context. For example, people commonly use basaltic when the rock is similar to the sensu stricto composition of basalt/gabbro, but not quite. It does not necessarily mean that we are talking about a gabbro with a composition similar to basalt. In a wider context, it may refer to "basaltic" vs "granitic" compositions, whereby their coarse and fine grained forms are called "gabbro" and "rhyolite", respectively. No idea why this terminology is rooted like that.

I'll finish with a photograph of a basalt dyke that I took some years ago:


What are good oceanographic journals I am a developer with a oceanographic side project.
I did some ML on wave & tide data and thought of publishing it in a paper. What are some good journals to send it to? Any recommendations?
Thanks
El

When searching for a place to publish Earth Science stuff, have a look at the two big continental scientific societies: the American Geophysical Union (AGU) and the European Geosciences Union (EGU). Both have a wide array of publications in the various fields of geosciences. AGU has JGR Oceans, while EGU has Ocean Science (open access). If you want to reach a broader, less specialized audience, you could also aim for Frontiers in Earth Science (open access): they have a Hydrosphere section.


How to classify the ENSO phase of a year? I am using the ONI index to classify the years of high rainfall seasons (December–February) as El Niño, Neutral or La Niña. El Niño year is classified as one if the ONI index value is +0.5 °C for 5 consecutive overlapping seasons.

My question since my season in between two Gregorian calendar years, what seasons should I check for the +0.5 °C threshold? Is it the preceding seasons or should I check since the beginning of year. I ask this because I am interested in investigating how El Niño might affect rainfall during a season.

First, based on the ONI, there are El Niño and La Niña periods, not necessarily years. For example, 2016 was El Niño during the first half and La Niña during the second half. On the flip side, From summer 1998 to early 2001 was one continuous La Niña period.

Second, The The wording that the NOAA gives for official classification of El Niño and La Niña periods is a bit misleading. El Niño periods are designated as such when there are 5 consecutive three-month-running means of sea surface temperatures that are 0.5 degrees C above the 30 year mean. For example, take a look at NOAA's ONI data here: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php
in 2016 there was an La Niña event that lasted from July to January because there were 5 three-month-running means in a row that were 0.5 degrees C below the 30 year mean. However, this only encompasses three "season", summer, fall, and winter.

Third, to answer your question, El Niño/La Niña classification is not bound by a calendar year, so going forwards and backwards until you hit a three-month-running mean that is less than the 0.5 threshold. The NOAA has already down the work for you, and even color coded it for you at the link above. Hope this helps.


Giant Cavern the Size of Manhattan Under Thwaites Glacier in West Antarctica - how was satellite and airborne radar data combined? This is a follow-up question to Giant Cavern the Size of Manhattan Under Thwaites Glacier in West Antarctica.

The work is reported in an open access paper in Science: Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica which is very technical, thorough, and hard for me to understand.

The work is based on a substantial amount of radar data, both SAR (Synthetic Aperture Radar) from several satellites, and (from Pasadena Now) ...by ice-penetrating radar in NASA’s Operation IceBridge, an airborne campaign that began in 2010 and studies connections between the polar regions and the global climate.

Is it possible to explain the differences between the two kinds of radar data (space and airborne) and how they were combined and used together to establish the size/volume and growth of this unexpectedly large amount of liquid water below the glacier?

The paper basically combines multiple datasets to figure out the changes in ice surface elevation and ice thickness at tidal and multi-year timescales. That way they were able to study grounding line migration, and the melt rate of the glacier and its corresponding ice shelf from above and below. Then they were able to make inferences of the processes producing glacier melting, specially basal melting that is difficult to measure directly.

They actually used three datasets:

DInSAR: Standing for Differential Interferometric Synthetic Aperture Radar. It is basically a technique that compares the phase of two SAR images acquired at different time to compute uplift/subsidence of the surface with great accuracy (usually millimeters). So they were able to see the surface of the ice shelf rise and lower with the tides, and also compute surface flow velocities.
IceBridge MCoRDS: Airborne radar depth sounder MCoRDS (Multichannel Coherent Radar Depth Sounder) operated by NASA mission IceBridge. This is a much more powerful radar operated close to the surface and designed to penetrate the ice, allowing to see the bedrock topography beneath the ice and some of the structure above the bedrock, such as water/ice transitions or layers of ice with distinct dielectric properties. This allowed them to know the ice thickness and bedrock topography.
TDX DEM: TanDEM-X Digital Elevation Model. This are Surface topography models generated using single pass InSAR data provided by two SAR satellites that orbit in tandem formation (one immediately behind the other). This allows precise surface topography measurements, that are also needed for the DInSAR processing.

I hope that helps. It is a very interesting work. Although the "giant cavern" part is not the most relevant part of it at all, but it was great for catchy headlines.


Is it less windy in a valley than on a hill? Assume we have a mountain landscape without trees.

Would it be less windy in a valley than on a hill, or would the wind just be the same?

Or in other words, which of the two images below describe the wind more accurately:

Scenario #1 is relatively, somewhat, kinda, but-not-really accurate for summer, scenario #2 more so for winter. If you live in or near mountains, you are familiar with cold evening winds that come ripping through canyons and valleys to settle in basins. In mountainous vineyards of Europe, vine layout is routinely adjusted to dissipate these winds. Even if there is NO (weather-induced) wind, thermal gradients can create winds of their own.

Winters see less of these thermal gradients and in general winds will be limited to higher altitudes where they blow pretty consistently. In both of your scenarios, however, winds blow pretty consistently at higher elevations....which is why wind farms are typically found there.


Why don't animals rot when trapped in amber? I just saw an image of a gecko stuck in amber 58 million years ago.  Why don't animals rot when they are trapped in amber?  I've seen dry insects whose chitin shells persist for a long time away from water and scavengers, but things with skin rot and dramatically change in appearance in the outside world.

things need to be exposed to bacteria to rot, amber produces a perfect form fitting seal and has several antimicrobial properties to boot killing off bacteria that is already present. Even microbes trapped in amber become preserved. This makes a lot of sense when you realize the resin evolved to seal injuries in trees if it did not prevent the spread of bacteria it would not work. HOwever preservation in amber is not perfect and the things do degrade, but do so so slowly that more geologically recently deposits have decayed so little is is almost undetectable, the type of resin also matters all resin is not equal and some amber resins preserves better than others.


Are La-Nina and positive Indian Ocean dipole similar? Because in both the cases, the warm water/ increase in temperature is seen on the east side of Africa.  Does not they mean that they carry rain bearing clouds from east of Africa to India, resulting in flood like situation in India.
Do they differ in any other way,  please let me know if I got them wrong?

The Indian Ocean dipole is essentially a measure of the difference in sea surface temperatures between the western and eastern Indian Ocean.

The El Nino and La Nina are the opposite phases of the El Nino Southern Oscillation cycle that occurs in the Pacific Ocean.

The only similarity with the Indian Ocean dipole, is that the difference between the sea surface temperature between the central western Pacific Ocean & central eastern Pacific Ocean are measured.


Would life on Earth survive without the Sun? Would life on Earth survive if Sun wasn't there? My teacher told me that there are chances that it would but there would be a lack of gases and chemicals and photosynthesis that occurs with light at certain wavelength.

The answer is No, the Earth would not remain in any recognizable form without the Sun.

There would still be a husk of a dead planet with a small amount of energy coming from the residual heat of the core which might be able to sustain chemosynthetic life in small colonies.  However, this is a pretty minor amount of energy compared to what we usually receive from the sun, and without an energy input lifeforms aren't able to sustain their unusually low entropic state (i.e. entropy wins the battle with life).

Some other examples of everyday things which would no longer occur (some already mentioned by @fre0n) are:

There would be no seasons.
There would be no weather.
There would be no daytime.
There would be no liquid water at the surface.
The surface temperature would drop to near absolute zero


How much does the weight of urban structures (buildings) affect the compaction (permeability, porosity, density) of alluvial sediments below a city? I live in Van, Turkey. Van City is situated on an alluvial plain beside Lake Van. General geological structure of the area can be seen on pages 43-44 in this conference book. One of the images is below.

According to the article in the link, sediment layers has a slope of 15-30 degrees toward the lake.

With the construction of every building, the pressure over the sediments increases. Obviously, this increase is greater in downtown area which has a lot of apartment blocks (mainly 5 to 7 story high reinforced concrete buildings). Downtown area is roughly in the middle of the plain.

I want to know that how much does the weight of urban structures (buildings) affect the compaction (permeability/porosity/density?) of alluvial sediments below a city and how does this affect the flow of underground water?

This question might be more appropriate for the SE Engineering site.

The thing about soils is that they vary from place to place. Some are sandy, some contain more clay than others and the thicknesses of layers is also variable. All this influences how different soils react to surface loading stresses, such as from building foundations/footings.

Immediately below the footings the soils will experience the greatest stress increases. As discussed in this document, particularly from page 10 onwards, the magnitude of stress the soil experiences from footings decreases with depth - see the effect of a point load $Q$, applied to the surface, on the upper right of page 12. At a depth $z$, the vertical stress $\sigma_v$ has a certain higher value. At a depth of $2z$, the value of $\sigma_v$ is lower.

One reason why the affect of surface loads decreases with depth is due to the nature of soil particles and how they lie in relation to each other. Soil particles are not uniform in size or shape, so they rarely lie directly on top of each other. There are gaps between soil particles, called pores. The pores can hold ground water.

Compaction and consolidation of soils will reduce the volume (size) of pore spaces. Foundation loadings will only affect the soil beneath them.

Because soil particles do not lie directly on top of each other, one particle may lie above two or more particles, the stress exprienced by the upper soil particle will be transferred to the other particles. Providing the soil is deep enough, the affect of this is the to, over depth, transfer vertical stresses to horizontal stresses.

Ultimately, if a soil profile is deep enough, the stress the lower reaches of the soil experience due to urban development will be small and will not affect ground water movement.


With all the rain Seattle gets, why is widespread flooding relatively rare? The Puget Sound region is wedged between the Pacific and the Cascades...you'd think with all that rain (and snowmelt in the warmer months), there would be catastrophic flash flooding in lowland areas, of the magnitude seen in Oklahoma (1, 2, 3), Texas (1, 2, 3, 4) or Tennessee (1, 2, 3).
On the contrary, western WA is actually subject to droughts and wildfires, not something you'd expect from such a wet region with rainforests.

Regarding climate, it does not rain in Seattle as much as people think; Seattle is in the snow shadow of the Olympic Mountains. It doesn't rain much in summer at all. Seattle gets rather dry in July and August.
Regarding flooding, the Skagit and Snohomish rivers north of Seattle flood regularly experience flooding. Some of the land in the flood plain is used for farming, and there are scattered households in the 100 year flood plain.
Regarding drought, drought severity is relative to the amount of precipitation and soil moisture levels typical for a specific locale. This means that even a rainforest can suffer drought. Because it's a relative concept, the rainfall during a drought in a rainforest would be a rainfall bonanza in arid climates.
Regarding forest fires, the Seattle area occasionally undergoes offshore flow. This occurs when the air pressure is lower in the Seattle area than it is east of the Cascades. This makes winds blow from the east, and if there's a forest fire east of the Cascades (which has a rather dry climate), that smoke can be carried westward toward the Seattle area by the offshore flow. That said, wildfires have occurred on the western slopes of the Cascades, and sometimes even in the temperate rainforest to the west of the Seattle area.


How to compare the oil production in barrel vs production in tons I hope this is the right SE site...I was unsure if to post here or on Physics, but I see there are quite many questions about oil here. So, my question is the following: I would like to compare the huge oil production of Texas, vs the minuscule (in comparison) oil production of a small region in Europe. I know it's silly, but some people are making this comparison and I want to show it's meaningless with actual numbers. Texas oil production is easy to find:

http://www.rrc.state.tx.us/oil-gas/research-and-statistics/production-data/texas-monthly-oil-gas-production/

1 131 557 443 barrels for 2016: I'm a little bit surprised they can pin it down to the single barrel (I guess much more than a barrel is lost in spillage, contamination, etc.), but oh, well.

The European region I'm considering has a production of about 3.75 million tons of oil. So, how do I compare barrels (a unit of volume) to tons (a unit of mass)? For a rough number, I thought oil must be lighter than water, since it floats on it, so if I consider water density, I'll get an upper bound. Now, since an oil barrel seems to correspond to 159 liters according to Wikipedia, I would get an upper bound of
$$(1\ 131\ 557\ 443 * 159)/1000\ m^3 * 1 \ ton /m^3 = 179\ 917\ 633 \ tons $$

About 180 million tons of oil (thus the comparison is ridiculous, as I suspected). But oil density is less than water, and it's actually very dependent on the type of oil being extracted, so to get a lower bound I will consider a density of $790 \ kg/m^3$ which I think is fairly low for Texas oil (correct me if I'm wrong). So I get about 142 million tons of oil, and this is still nearly two orders of magnitude larger than 3.75 million tons of oil. Is this correct? Would it be possible to get sharper estimates, or is this the best one could hope to get, given all the uncertainties in this calculation?

I suspect that 3.75 million tons of oil is actually tons of oil equivalent (toe). This is a unit of energy rather than mass. The US uses a barrel of oil equivalent (boe) as a measure of energy. The advantage of these energy units is that natural gas, coal, and refined petroleum products can all be measured in terms of tons or barrels of oil equivalent.

The US still measures oil production in volume. Depending on the quality of the crude oil, it takes between 6.5 and 7.9 barrels of oil to yield one ton of oil equivalent, with 7.33 barrels as an average value. That means that the 1 131 557 443 barrels produced in Texas in 2016 represents somewhere between 143 to 174 million tons of oil equivalent.


How to find Cloud cover data in GFS grib models I've been looking for the cloud cover estimates provided in the NOAA GFS models.  This page discusses all their weather products and one of the few I find that includes cloud cover data "Total Cloud Cover [%]" (variable TCDC) is gfs.t00z.pgrb2.0p25.f006 which you can find in its product description.

Upon extracting that file using the grib filter tool generated URL selecting for the proper layers and variables, this data appears to be just initial values (1 for cloud cover) and 9999 for many of the other values.  I read a lot of gfs grib & cloud details here that suggest the .fxxx files like "gfs.t00z.pgrb2.0p25.f006" are

  The cloud % field is probably output from some of the model physics (microphysics I guess) routines, which may not be setup to write out the fields after the very first model time step (the f00 files denote fields after the first model time step, not the actual analysis/initial condition).  We do in fact initialize the cloud condensate field, however

My question is where are the TCDC cloud data numbers in the GFS grib models?  They don't seem to be in the analysis files (gfs.t00z.pgrb2.0p25.anl) or the FH000 file.

Note:  I'm using grib_api tools to read these fields (grib_ls and grib_get).  I've used them successfully for currents and winds, but I can't seem to find the right GFS data for TCDC cloud cover.

EDIT:  I've been testing the full files from http://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/

the gfs.t12z.pgrb2.0p25.anl file didn't contain cloud data, so I tried one of the .fxxx files (gfs.t12z.pgrb2.1p00.f384).  There appeared to be fields set, but they were at initial values according to grib_ls tool.  Here's a snippet:

[3036] => 260130      Total ozone  9999
[3037] => 228164      Total Cloud Cover  9999
[3038] => 228164      Total Cloud Cover  9999
[3039] => 228164      Total Cloud Cover  9999
[3040] => 228164      Total Cloud Cover  9999
[3041] => 54          Pressure    9999
[3042] => 54          Pressure    1
[3043] => 54          Pressure    9999
[3044] => 54          Pressure    1
[3045] => 54          Pressure    9999
[3046] => 54          Pressure    1
[3047] => 54          Pressure    9999
[3048] => 54          Pressure    1
[3049] => 130         Temperature  1
[3050] => 130         Temperature  9999
[3051] => 130         Temperature  1
[3052] => 228164      Total Cloud Cover  1
[3053] => 228164      Total Cloud Cover  1

I'm using a little older version of grib_api on my server: 1.10.0

I get a little different response with grib_api 1.14.4:

  3054        Precipitable water  34.4
  260102      Cloud water  0
  157         Relative humidity  39
  260130      Total ozone  283.1
  228164      Total Cloud Cover  4
  228164      Total Cloud Cover  0
  228164      Total Cloud Cover  5
  228164      Total Cloud Cover  9
  54          Pressure    9999
  54          Pressure    90670.4
  54          Pressure    9999
  54          Pressure    13200.4
  54          Pressure    9999
  54          Pressure    88060
  54          Pressure    9999
  54          Pressure    11470.4
  130         Temperature  288.9
  130         Temperature  9999
  130         Temperature  198.2
  228164      Total Cloud Cover  0
  228164      Total Cloud Cover  2

But it still seems a bit odd for the results.  Lots of 9999's and whole percentages like 0 or 2.

Edit 2:  It appears that computing the cloud cover has to be done from the GFS layer data however it appears how it is done is unclear based on an old message from 2007:  http://www.weather-watch.com/smf/index.php/topic,20158.msg216087.html#msg216087

This is not an explicit answer but might give you an idea. The US National Weather Service forecasters use a tool called GFE to create gridded forecasts, largely starting from raw model data. For most models, even those that have TCDC as an output field, the model sky cover grids are computed by GFE using RH at various levels. For a few of the high resolution mesoscale models, the sky grids use the model cloud cover field and the resulting values are either 0% or 100%. Thus a blend of these differing sources can be used to get a more nuanced output forecast.


How spatial resolution of a NWP model works? I would like to know how the resolution of a Numerical Weather Prediction model conceptually works.
i.e.
"Global Forecast System's forecasts with 0.5° horizontal spatial resolution"
"NCEP’s reforecast is based on the Global Ensemble Forecast System (GEFS), which has horizontal grid increments of approximately 1°."
Are these two sentences talking about the same thing? In this case, GFS has more resolution, doesn't it?

Yes, the deterministic GFS model (one model) has higher spatial resolution than the GEFS models (31 models). That is, that the latitude and longitude of the entire world is incremented by 0.25° in the GFS and 0.5° in the GEFS (they upgraded both in the past two years). When people say "high resolution," think of it like "more pixels" on a video (like 1080p).
On a more technical note, the GFS's (internal) resolution was once described as T-numbers, which counts the number of waves that can be fitted. The GFS could fit 1534 waves. However, since the upgrade in the dynamical core, the resolution has taken a different number. I don't exactly know the physical interpretation of the C-number, but the GEFS's C-number is currently C384 (my guess is that it is the number of cubes on one face of the cubed sphere).


Two severe cyclones connected by a monsoonal trough At the time of writing, areas around the Northern Territory (TC Lam) and Queensland (TC Marcia) in Australia are in the path of severe cyclones (category 4 at the moment, with the Queensland one - TC Marcia predicted to reach category 5 - Category scales used for Australia and Fiji).  These cyclones seem to be connected by a monsoonal trough, as indicated by the dashed line in the weather map below from Australia's Bureau of Meteorology:

Note: it is summer here at the moment.

Also, these cyclones are a very large distance apart (about 1900km in a direct line), and these cyclones are not merging at all.  According to the Meteorological Bureau, TC Lam is moving south through the Arnhem Land area of the Northern Territory; and TC Marcia is going to 'hook' when it goes inland and head towards the Brisbane area to the south coast of Queensland (but it is expected to weaken to a tropical low well before then).  The projected paths (based on latest and consistent information from the Bureau) is shown as red arrows in the image below:

What is the meteorological mechanism that has resulted in the linked "double" severe cyclone event?

Edit - update: TC Lam has made landfall at cat 4, TC Marcia is now making landfall at cat 5

Let us state the obvious reasons first:

Warm SSTs along the Timor Sea as well along the Queensland coast favour the formation of Tropical Cyclones -

The following two URLs show the SSTs along the Northern as well as Eastern Coast of Australia for the referenced periods.
a) http://earth.nullschool.net/#2015/02/15/2100Z/ocean/primary/waves/overlay=sea_surface_temp/orthographic=136.27,-24.99,512

b) http://earth.nullschool.net/#2015/02/20/2100Z/ocean/primary/waves/overlay=sea_surface_temp/orthographic=136.27,-24.99,512

The threshold SST required for tropical cyclogenesis is 26.5 C as shown in The Threshold Sea Surface Temperature Condition for Tropical Cyclogenesis
The role of equatorial waves in tropical cyclongenesis and in this case interaction of equatorial waves with the monsoon trough. Results of filtered OLR as shown in the image below shows the presence of an Equatorial Rossby Wave over those regions and the presence of blue shades indicates negative OLR (enhanced convection).

Source - Tropical Wave Monitoring

This reference The Role of Equatorial Rossby Waves in Tropical Cyclogenesis. Part II: IdealizedSimulations in a Monsoon Trough Environment clearly states that

  " When just the MT is simulated without the ER wave anomaly fields,
  the MT remains quasi-steady and TC genesis does not occur. It is only
  when the ER wave is imposed on the MT that TC genesis is initiated.
  The results imply that the ER wave–MT interactions produce more TCs
  than would otherwise occur if no such interactions took place."

A question that can be raised  is that  we do know that presence of MJO also promotes tropical cyclongenesis as shown in this reference Diagnosis of the MJO Modulation of Tropical CyclogenesisUsing an Empirical Index. So how can does one state unequivocally that it is a Equatorial Rossby Wave and not the MJO's interaction with the MT that favours tropical cyclogenesis ?

If we look at the strength of the MJO signal during and after the formation of TC Lam & Maria

as shown in these set of images

The amplitude of MJO signal is currently weak (less than 1 being present inside the circle) and is unlikely to be a significant contributor to the formation of tropical cyclones.

This conclusion can be enhanced by looking at the filtered OLR contributions from MJO -

The presence of positive OLR(in yellow over the Northern/Eastern part of Australia indicating suppressed convection.
Both the MJO as well as tropical waves favour the formation of twin cyclones as shown by references Dynamical Aspects Of Twin Tropical cyclones  Associated with the Madden Julien Oscillation  and A Case Study of an Outbreak of Twin Tropical Cyclones

Update
In an earlier question that I had asked Relation between direction of shear and cyclone formation one can clearly see a working example of easterly shear favoring the formation of tropical cyclone. So easterly shear as shown in the map below is defined as the difference in the zonal winds at two different pressure levels (850 hPa and 200 hPa). Since by convention easterly winds are noted to be negative increasing positive values of shear is easterly shear(as one travels vertically) and the opposite is westerly shear. The following shear plot is a mean of several days and one can see the easterly shear over the Australian regions where the cyclone formation took place.

$zonal\_shear = U_{850} - U_{200} $

The data is from NCAR NCEP reanalysis.


Local Weather Forecast (Self-Learning Algorithm) First of all, the question! :

Is it possible to predict local weather tendencies for the upcoming hours (let's say 2-3 hours) using only local data?
If yes, which data is needed to make such predictions and which predictions are possible?

I'm not talking about very precise predictions, just basic stuff like: "The temperature will rise/drop" or "If humidity goes up and air pressure drops, it will probably rain" etc.. you get the idea.

I was thinking of using data for temperature, air pressure, humidity, time of day and wind speed/direction.. maybe something else?

Some Background :

for a little DIY Home-Project I decided it would be an interesting idea to set up a little "weather station" in front of my home and collect all sorts of weather related data in short intervalls (e.g. temperature, air pressure, humidity, wind speed/direction, time of day etc.)

The idea is to collect data over the period of a few months (or more) and to develop an algorithm that is able to predict the upcoming weather with a certain probability.
The result should be a little program that was trained on past data and is then able to predict weather tendencies (Temperature, rain, etc..) using the data of the last couple of hours. Let's say the temperature and the air pressure drop and the humidty rises over a certain period of time, then it should tell me that it will likely rain.

I will not bother you with the details on how to write such a self-learning algorithm, but since I'm not very well educated regarding meteorology I'm not even sure if such predictions are possible or to what extent.

I think you've understood the idea. Please give me your Ideas about it. What's possible what's not. Maybe experiences, which data I need, what predictions i could possibly make and which not and so on.

Thanks for any help!

(not an answer, too long for a comment)

Strictly speaking, the answer is yes, since the temperature generally increases during the day and falls at night (and local time is a local variable), the barometric pressure and humidity can indicate if a storm is coming (there were some really old fashioned weather prediction "clocks" that did this). Realistically, upcoming weather in your local area depends on what's nearby, since that's the weather that moves into your area. Also make sure you don't overfit your model: even a model that perfectly fits your existing data isn't necessarily predictive. Finally, there are lots of weather data available, including local weather data, and you might want to use those data as well.


Could a large burst of super-heated or super-cooled air cause tornadoes to fall apart? We know how tornadoes form: when areas of hot air and cold air mingle, causing rotation. We can even see them form on the radar.

Yet, for all of our technology, we can't stop such events from happening - even though we can cause it to rain by seeding clouds.

But if someone were at the area that a tornado was about to form and was able to introduce an area of super-heated or super-cooled air into the potential tornado, would it destabilize the formation of the destructive whirlwind? Or would doing such a thing cause more of them to form or for them to form more quickly and/ or be more damaging?

Changing air currents is very difficult and energy intensive.  You'd need to alter an entire weather system - no easy feat.  If you heated a very large region of cool air you might prevent the spiraling that causes tornadoes to form, but you'd need to warm at least few states worth of upper atmosphere.   It would be an enormous undertaking.

There's also the logistical problem of how would you go about doing it?   Heating in principal can be done faster than cooling, presumably sending up a whole lot of hydrogen in a few hundred balloons and igniting it forming hot water-vapor, which as it condenses, would further heat the atmosphere.    Cooling warm air is harder as there's no quick and easy method to cool an enormous  volume of air, so I think heating the high cold air would be easier than cooling the low moist air, but it would still be an enormous effort and probably cost more in prevention than the tornadoes are likely to do in total damage.

http://images.slideplayer.com/22/6379142/slides/slide_22.jpg

There's no neat and tidy technological trick to get it done that I can think of.


Is it possible to determine where gold might be found based on a map, and if so, how? Is it possible to locate potential gold deposits using maps that describe dominant rock type, altitude, vegetation, or geological formations?

(I realize that the location would probably still have to be verified by traveling to the actual site. I am only looking for information that serves as an indicator of potential gold reserves.)

For the sake of this question I am assuming of course that these maps would not directly list gold deposits or existing or past gold mining operations.

What kind of information would a map need to contain in order to derive an indication of gold deposits from it?

On of the issues with geological maps is they have all required humans to walk over the ground and mark on a piece of paper the surface expressions of different types of rock and geological structures, such as faults and folds.

Because of this process and the time constraints placed on people when they mapped the land there will always be some level of detail missing.

Geological maps will show the different rock types and geological structures on the surface but they may not necessarily show what is at depth.

Geology has advanced to a state where most well trained geologist will know the potential for certain rock types to host certain type of mineral deposits, including gold. However, pinpointing where a gold deposit, or any other mineral deposit is located will always require a human to walk the ground and inspect it in more detail and to take samples and have them analyzed in a laboratory.

Initially those samples may be geochemical samples, others will be rock samples and chips taken from the surface or trenches dug into the surface, culminating in drill samples being taken.

To further assist where to look, geophysical testing methods may be used, such a magnetic anomaly testing or ground electrical resistivity testing.

It is very unlikely that anyone will be able to look at a geological map, and with any degree of certainty say "there is a gold deposit" or "there is a gold deposit that is economic to mine". More likely, a person will look at a geological map and say something like, "there is a greenstone belt, this may have potential to host a gold deposit, further investigation is needed".

There is an adage amongst some geologists that states "gold is where you find it". There is no altitude preferable for finding gold deposits. It's found in mountains, in deserts, in forests, under salt lakes, even dissolved in the oceans. The oceans contain the largest quantities of gold, but it is uneconomic to extract it from sea water because the concentration are so low.

Biological indicators, such a vegetation may work for some base metals, such as copper, but not necessarily for gold.

Also, gold can occur as a deposit of just gold, but it can also occur in association with other metals in the form of polymetallic deposits which contain gold, silver, copper, lead or zinc, even uranium.

Finally, not all deposits of minerals, gold included, are reserves. To be classified as a reserve and an orebody, a deposit of mineralization must be economic to mine.


How come ZamZam water in Mecca never runs out? It is located in the middle of a dry desert in Mecca and the astonishing thing is all wells around Mecca dried out except this one!

So how can a small well, with a diameter of about 1.46 meter to 2.66 meter, and the depth of about 30 meters quench the thirst of billions of people from all over the world throughout centuries?

The Zamzam Well is located in the Wadi Ibrahim. It accesses water from the wadi alluvium and from the bedrock.

  Water in the well comes from absorbed rainfall in the Wadi Ibrahim, as well as run-off from the local hills. Since the area has become more and more settled, water from absorbed rainfall on the Wadi Ibrahim has decreased.


Why are the clouds white and Australia black in weather satellite infrared images? The question Is the sunlight on the GOES-16 Imagery reaching from the east? shows a visible light image and so in the night areas the Earth appears dark and in the day areas the Earth is a bit brighter and the clouds are the brightest.

We can have 24 hour imaging of clouds and weather in thermal infrared satellite images. Below is a a thermal infrared image at about mid day in Japan and Australia. I'd expect the tops of the clouds to be cold and the outback to be hot, and yet it's just the opposite!

The clouds are nearly white
Central Australia is nearly black
The ocean and all of the Asian continent are dull, almost featureless gray; if there weren't a superimposed outline it might be hard to even tell where the water ends and the land begins in some places.

Why is this? What's going on?

Himawari-8 IR1 image from Central Weather Bureau click for full size

I had a very similar question in a job interview!  The only difference is that it was an image from SEVIRI on Meteosat.

The imager on HIMAWARI is called the Advanced Himawari Imager (AHI).  The AHI IR1 channel is actually channel 13 with a central wavelength of 10.4 µm, which is in the window region (apparently it's called IR1 in reference to an older satellite).  The clear-sky atmosphere is mostly transparent in this region of the electromagnetic spectrum, so we can see the surface or clouds mostly unobstructed by water vapour, ozone, or other gases.

In an infrared image such as this one, high clouds are cold.  Forecasters who look at such images for a living like to see clouds as white.  I'm a physicist and I prefer to map values of high intensity to white, which would make clouds black, but forecasters are the most important users so they get their way.  :)

To display cold areas as white, hot areas must logically be displayed as black.  So what we are seeing in this image:

Central Australia is hot.  This is expected, because it is a hot desert with high emissivity.  The image is apparently taken at 12:00Z, which should be between 20:00 and 22:00 legal standard time in mainland Australia, so it's not long after sunset, when the land is still hot.  Australia should appear less "black" at an image taken 8 hours later.  The image is apparently taken at 12:00 "local" (140°E) time (03:00 UTC).  It's February and summer in Australia, and the northern hemisphere looks a lot less hot (it's also earlier in the morning there, compared to sunrise).
Cloud tops are cold.  This is expected, because they are in the upper troposphere.  Those white clouds are ice clouds.
There are grey-ish clouds too with little contrast to the ocean.  Those are lower, liquid clouds, they are warmer.  The lowest clouds may be difficult to identify in infrared images, which is why (for example) night time fog detection from satellites is difficult.

(I got the job!)


Why does the annual temperature range get bigger where latitude is higher? Why does the annual temperature range get bigger where latitude is higher?
Is it because of the ocean currents?
Or is there any other factor that causes this situation?

Welcome to the Earth Science Stack Exchange!
The bigger temperature range is because of the wide difference in the length of daylight seen in the higher latitudes. Depending on how high you are talking about, there can times where there is no sun for a month and vice versa with constant sun. Because of this there will therefore be more time for warmth and cooling as the Sun (or lack thereof) is what drives the diurnal temperature change the most.


Will dust storms be more frequent in the future? I noticed that in some science fiction movies set in the future on Earth, like Wall-E and Interstellar, dust storms are very prominent.

Are there any scientific hypotheses suggesting that dust storms may become more frequent in the future?

Most dust storms occur down-wind from areas with a lack of moisture, little vegetation, and high soil content.  Vegetative roots help to keep the soil intact when there is a lack of moisture. So any shift in the future that leads to a net decrease in vegetation, net decrease in precipitation, or an increase in exposed soil content will increase dust storm occurrence.  Thus, the most plausible reasons for increased dust storms in the future that have related scientific research are:

land-surface changes due to human influence: forests/vegetation being replaced by land management practices for agriculture or mining that do not sustain roots in the soil or expose more soil
decreases in precipitation (e.g. due to climate change) that potentially lead to desertification of the region.
diversion of rivers for human use, thereby removing water from any ecosystems that were previously downstream
extreme cataclysmic events (e.g. comet impact or nuclear war) that causes removal of most vegetation

So, in my opinion, it is a very real possibility that if humans continue to cause a net decrease in vegetation... there will be increases in dust storms.  However, there are good land management practices that can curtail dust entrainment into the atmosphere, such as those adopted after the historic 1930s "Dust Bowl" in America.

Finally, from IRO-bot's comment link to Wikipedia dust storms:

  It has been argued that recently, poor management of the Earth's drylands, such as neglecting the fallow system, are increasing dust storms size and frequency from desert margins and changing both the local and global climate, and also impacting local economies.


How can I merge weather data from different time zones? Does anyone know of any simple means for merging (inverse distance weighting method) hourly weather files (precip, temp, etc.) from different time zones?

I am creating weather data for HUC8s, and am using the 5 closest NCDC weather stations.  But some HUC8s cross over different time zones.  Has anyone figured out the easiest method for aligning weather data?

My thought is to put everything into GMT - so that 10am is 10am everywhere, and track the offset in a new column in my data.  I believe this would work, but am having trouble completely wrapping my head around it:

Focusing on a watershed that cross from CST into EST - if it was raining at 10am EST, and also raining at 9am CST (raining at the timezone division, with weather stations on either side of the timezone division), it's raining at the same time, we are just marking the 'time' differently in each location.  However, if I transformed my date/time into GMT, with a new column tracking the offset (maybe to convert it back later), it would be the same GMT time in both locations that the rain was occurring?  In effect, it is just shifting all the weather into the same time zone, and then merging based on IDW.

Does anyone have any simple solutions I am overlooking?

Using your example of 10 AM EST and 9 AM CST, those are both exactly the same time and another way of specifying that time is 1500 UTC or 15Z (Z being historical for GMT, for your application the difference between UTC and GMT is negligible).

If you know the location of your stations then you can know their timezone.  To make inter-comparisons between stations meaningful you need to reference them all at the same time and the easiest way is to express them in UTC.  You are correct that this is just a nomenclature change but this gives all locations a common reference anywhere on earth.  All meteorological data natively uses UTC and has been since telegraph was invented and weather data was exchanged over large distances.


What tectonic mechanisms cause the North and South Islands of New Zealand to be so geologically different? New Zealand is a very active seismic and volcanic region of the Pacific Ring of Fire, on the boundary of the Australian and Pacific Plates; however, there is a difference between the 2 islands: volcanoes and earthquakes on the North Island and earthquakes only on the South Island (see maps below):

Location of New Zealand volcanoes

(Image source)

New Zealand Earthquake Map

(Image Source)

What are the tectonic features that account for the difference between the North and South Islands?

Additionally, how will this boundary develop in the future (geologically speaking)?

New Zealand sits along an oblique convergent plate boundary, where the Pacific and Australia Plates meet. The boundary between the two plates is shown in your second figure as the grey line, with the Pacific Plate to the east and the Australia Plate to the west of it. In terms of relative movement, we can think of the Australia Plate as being stationary and the Pacific Plate having a west to south-west direction of movement. The angle at which the Pacific Plate moves into the Australia plate changes along the length of New Zealand - this is what causes the differences in tectonic style and thus differences in volcanism and earthquake occurance (and motion) between North and South Islands. The angle changes from north to south due to:

a clockwise rotation of the Pacific Plate, and
Pacific and Australia plates meeting at varying angles.

If this boundary was straight and the Pacific Plate moved orthogonal to it, then there would only be subduction, as the Pacific Plate is denser than the Australian. Conversely, if the Pacific Plate moved parallel to the Australia Plate there would be no subduction. Along the length of NZ both of these end-members (and variations in between!) are observed, as not only is the plate boundary slightly curved over the length of New Zealand, but the movement of the Pacific Plate has an component of clockwise rotation. Lamb (2011) shows that there has been 70-90 degrees of clockwise rotation of the boundary/margin over the last 20 million years, and it is still occuring today. The differing angles of intersection between Pacific and Australia plate along the length of NZ cause differences in tectonic style, which give rise to differences in volcanism and earthquake occurance and motion. The figure in this section of the Geology of New Zealand Wikipedia page shows the variations of displacement vector (direction and magnitude of motion) along the length of New Zealand. Notice how the vectors are more orthogonal to the plate boundary in the North Island and become more acute in the South Island.

Subduction occurs in the North Island because the Pacific Plate moves rougly orthogonal to the boundary with the Australian Plate and is denser than than the crust around New Zealand; the Pacific Plate is composed mainly of basalt, while New Zealand is an amalgamation of different sedimentary and volcanic rocks. As the Pacific Plate is subducted is bends and breaks, causing earthquakes. It also melts, causing volcanoes. Notice how the depth of earthquakes in the North Island gets deeper to the west - this is due to the continued westward movement of the Pacific Plate even as it subducts under the Australia Plate.

Over most of the South Island the Pacific Plate moves roughly parallel to the boundary of the Australia Plate. The Southern Alps are caused by slight obduction (up and over movement) of the Pacific Plate over the Australia Plate.

To the south of the South Island the polarity of subduction is reversed, with the Australian Plate being subducted beneath the Pacific Plate  (e.g. Randall, 2007).

This post is a huge simplification of the tectonics of NZ. The geology of this continental fragment is very complicated, but also very interesting! Have a look at this video to see how the plate boundary has changed over time.


If the distance between Earth and the moon were changed, would the effects be immediate? I need your help on a possible (but perhaps low probability) scenario for how the distance between Earth and the moon could change: say a large object from the Kuiper Belt manages to make its way into the inner system. It passes by our moon such that its gravity changes the moon's orbit around Earth into a more pronounced ellipse. So there will be times when the moon is much closer to Earth and other times when it's further away than its current distance from Earth.

Say that this change in the moon's orbit isn't enough to cause an apocalyptic scenario for life on Earth but that the tides are of course much, much more pronounced. I surmise that the greatest impact would be felt in costal towns and cities around the world. My question is: how long would it take for the change in the moon's orbit to be felt on Earth? Are we talking almost immediately/ within the hour for some unlucky areas that are now much closer to the moon on its new orbit, and at most within 12 hours for the "luckier" areas? Or would the time frame be much longer?

Thank you in advance for any insights you could offer on this.

The moon's orbit might have changed, but obviously it would take some time before this would become visible. The moon's position iself would probably not be that affected by the event as its inertia is too huge. So the tides would probably not be noticeably affected in the first hours.

I have no idea really how long, but it might not take too long before, depending on what point of its new, elliptical orbit the moon is now positioned - is it now approaching earth, or more or less staying at the same distance, or to the contrary getting farther away - the tides will start to be affected.


What is the geologic origin of the Bauxite deposit in Bauxite, Arkansas, and could there be more? Bauxite is an mineral of Aluminum. Despite a general mineral wealth, the USA does not have any major Bauxite deposits, except for one in Arkansas. The mining town was named Bauxite, Arkansas.

The mine operated from 1895 to 1981. It produced about 80 million metric tons of bauxite ore over its lifetime (just guestimating from this pdf, page 6).

So what is the origin of this deposit? It seems strange to me, not being near any mountains. How did the minerals form? And why aren't there any others despite very similar terrain all over Arkansas and other states?

The short answer is, bauxite requires a particular alumina-rich source rock and a specific set of conditions and processes to concentrate the aluminum in a specific order.

From the  Encyclopedia of Arkansas:

  The Arkansas bauxite region covers about 275 square miles in the northern part of the West Gulf Coastal Plain and is divided into two mining districts. One area is in Pulaski County, south and east of Little Rock, and the other is in nearby Saline County, northeast and east of Benton.

(Source, Arkansas Geological Survey; a very detailed map can be downloaded here)

The source rock (nepheline syenite) for the bauxite appears as two isolated blue spots in the middle of the map above, surrounded by (orange) Tertiary sedimentary deposits. The town of Bauxite is just to the northwest of the southern spot.

Rather than cut and paste EOA's description of the process, I decided on the following summary:

Magma was intruded during a Cretaceous volcanic event as the Mississipi Rift opened, and this formed nepheline syenite, which has aluminum-rich nepheline where granite would have quartz.
The syenite decomposed, eroded, and was deposited as a soil on the edge of a shallow sea that filled the rift.
In the Paleocene, tropical conditions caused the aluminum minerals toleach down into the soil, becoming concentrated into a hard layer called a laterite
In the Eocene, some of the laterite was eroded and deposited as alluvial bauxite ore as the sea slowly filled in.

Both the original laterite and the alluvial deposits have been mined for aluminum.

Your assertion that there are no other bauxite deposits in the US is not true; other deposits formed in similar conditions in the southeastern US, and there is also bauxite in Montana.


Cloudless sky in synop message? SYNOP code (see http://weather.unisys.com/wxp/Appendices/Formats/SYNOP.html) has a field for describing cloud types by different levels, given as "8NCCC" (see link for further info, Cloud type information). And there is a program for converting SYNOP to XML, http://metaf2xml.sourceforge.net/, which in most cases seems to work. However, when the cloud code is "80000", which IMO is correct for a cloudless sky, then the program says "invalidFormat". So does anybody know if "80000" is correct or not?

Edit:
"AAXX 11003 63658 32970 00905 10207 20060 38860 48492 80000 333 58002 555 10130"
Real life example showing that total cloud cover in previous section is also 0. Does this mean that when total cloud cover = 0 is already given, then the section about cloud types is anyway meaningless?

Yes, in your example, the group should have been omitted. From the WMO Publication No. 306 - Manual On Codes - Volume I.1 - Part A, Section A, FM 12 SYNOP:

  12.2.7 Group 8NhCLCMCH

  12.2.7.1 This group shall be omitted in the following cases:

  (a) When there are no clouds (N = 0);

  (b) When the sky is obscured by fog and/or other meteorological phenomena (N = 9);

  (c) When the cloud cover is indiscernible for reasons other than (b) above, or observation is not made (N = /).

metaf2xml tries to stick to the Manual but tolerates deviations, so the group is recognized but marked as invalid.


Why is my ♦ hammer (i.e. diamond) so durable, but it can burn? For those confused about the title, there's a joke that every moderator has a "diamond hammer" (diamond from the little ♦ by the username). In a chat discussion, it was brought to my attention that a diamond can burn (which makes total sense because it's pure carbon) after I got a notification in orange in the topbar of SE.

Anyway my question is why can something so durable be able to burn? I would imagine that there would be a relationship between flammability and durability, especially since metal cannot burn.* Is it just a coincidence that most people think hard == inflammable? Why can diamond burn?

*It can burn when oxidized IIRC.

It is bond strength, not hardness, that determines how easily oxygen
  can attack and burn a material, allowing me to burn a diamond in a
  pool of liquid oxygen resting in a block of graphite.

Diamond is hard because its bonds form an inflexible, three-dimensional lattice. However, the strength of these bonds themselves is not even as strong as graphite, for example. Graphite has much stronger bonds, but they create "sheets," which can slide around, making graphite softer but harder to burn.

(source)

Indeed, people have burned diamonds before by putting them in tubes of pure oxygen.


estimation of prehistoric sea levels From what reference point/level are prehistorical (e.g., Precambrian era) sea levels estimated?  As I understand things, the following are true:

Since the formation of continents, land elevations everywhere have been continually changing due to plate tectonics, weathering, sedimentation, etc.
The total volume of ocean water has been essentially the same since formation in the early Hadean.
Water seeks its own level.

So is the rise and fall of sea level derived from the geological record measured relative to the adjacent land, or the center of the earth, or what?

Short answer:    Nobody knows.   Estimates of post-cambrian water levels are done by studying geology and where shorelines were in the past and what land was under water and working out from that how high the sea level probably was.   There are no pre-cambrian sea level estimates that I know of.

Working out how much water was on the surface of the Earth, especially during the pre-Cambrian era is a difficult subject with much uncertainty.   While the total amount of water on Earth may not have changed too much too much over the last 3 billion years, ground water vs surface water, and the shape of the ocean basin and the role of volcanoes and tectonics add to the uncertainty.   There's still some uncertainty on snowball Earth and if it went all the way down to the equator over the oceans.   Sea level over the pre-cambrian requires working out the specifics of snowball earth.   It's a tricky subject full of uncertainty.

Long answer that also says we basically don't know:

  From what reference point/level are prehistorical (e.g., Precambrian
  era) sea levels estimated?

I've never seen a pre-cambrian era estimate on sea level so I don't know how they are estimated.   This is the oldest I could find.

As the article explains, historic sea level is estimated by finding where the shorelines were at geologically historic time periods and looking at what was under water.   There's probably a pretty significant margin of error in those estimates I would think.

The article also says

  The main factors affecting sea level are the amount and volume of
  available water and the shape and volume of the ocean basins. The
  primary influences on water volume are the temperature of the
  seawater, which affects density, and the amounts of water retained in
  other reservoirs like rivers, aquifers, lakes, glaciers, polar ice
  caps and sea ice. Over geological timescales, changes in the shape of
  the oceanic basins and in land/sea distribution affect sea level. In
  addition to eustatic changes, local changes in sea level are caused by
  tectonic uplift and subsidence.

  Over geologic time sea level has fluctuated by hundreds of meters.
  Today's interglacial level is near historic highs and is 130 meters
  above the low level reached during the Last Glacial Maximum
  19,000–20,000 years ago.

So, key factors are obviously ice ages and glaciers, as well as the shape of the ocean basin.   The movement of continents affects the shape and depth of the ocean basin, so continental movement likely has an effect.

As a somewhat small but fun example, the Mediterranean Sea has about 3.75 million cubic km of water in it and the sea is thought to have been a dry valley some 5.33 million years ago that, once the straight of Gibraltar gave way, was quickly filled by the Atlantic ocean.   That's just a theory.  It may have filled much more slowly, and over 5 million years ago, it might have been a significantly different size too, but if we use the 3.75 million cubic km number over today's 361.9 million square km of ocean surface, that works out to a 10 meter drop in sea level to fill up the Mediterranean valley.    10 meters isn't a big change in the grand scheme of things, but if it happened over as little as a year, as one hypotheses suggests, that would have been quite something to observe a 10 meter drop in sea level over a single year or so.   However long the Mediterranean took to fill, it's a nice example of how shifting land can affect sea level.

Historic estimates are made (as noted above) by studying where the shorelines were and studying what was under water and trying to piece together an estimate from that.   Formation of glaciers like the Antarctic Glacier, which would raise sea level 58 meters if it melted, affect sea level too.  The antarctic glacier began to grow in earnest about 34 million years ago.   Greenland is another 6 meters and that formed much later, over the last million years or so.

Geological history of ice ages is fairly well understood, though the total amount of water in those glaciers might have some uncertainty.   The shape of the ocean basin is (I think) less well understood over the last 600 million years or so.

The ice age periods, 260 to 360 and 420 to 450 million years ago should correspond to drops in the chart, below.  The recent ice age period is just 2.5 million years long, and too short to be well represented but the 34 million years when the antarctic ice formed is apparent.

  Since the formation of continents, land elevations everywhere have
  been continually changing due to plate tectonics, weathering,
  sedimentation, etc.

The continents formed quite early, between 2.5 and 3 billion years ago.  The silicate rock that form most of the granite that makes up both the continents and the continental plates was present at the formation of the Earth.   Heat and plate tectonics likely helped form the continents.   Life and photosynthesis may have added to them over time, but most of the continental material was present at Earth's formation.

Precisely how sea levels change, other than by formation of glaciers or the forming of filling of valleys on land is (to my knowledge) not well understood though the shape of the ocean basin (noted above) plays a key role.   The continents are roughly some 35 miles thick in silicate rock, but that far below the Earth's surface, silicate rock can melt and mix with basalt in the upper mantle.   We know this because lava can be either basalt rich or silicate rich.

Wikipedia mentions sediment and groundwater likely also play roles.  Over long enough periods of time, the rock cycle likely returns sediment that erodes of land into the ocean, back to the land.   Likewise, life can lead to the formation of limestone and other carbonate rock, but that's probably a small percentage of total land and a small factor, not a major factor.

The internal heat of the Earth (I would guess) play a bigger role.  A hotter earth, the upper mantle is a little closer to the surface and the granite continents and continental plates are less thick, so they float less high on the basalt, leading to a corresponding higher sea level, but that's just speculation on my part.   As Earth cools over hundreds of millions of years, the granite may become thicker and the sea level could drop in relation to the rising land.  This fits with the studies that sea level was generally higher in the past, but, again, this is speculation on my part.

  The total volume of ocean water has been essentially the same since
  formation in the early Hadean.

You probably shouldn't make that assumption.  The Hadean was the first epoch all the way back to the formation of the Earth.   For consistent amounts of water, the earliest I would consider starting would be the end of the late heavy bombardment, about 3.8 billion years ago.   That would be enough time for the magnetic field to form (about 4 billion years ago) and time for the sun to settle down, because UV rays from the young sun can strip water form Earth by photo-chemical dissociation.

Throughout the history of Earth, UV rays from the sun have stripped hydrogen from atmospheric water vapor, effectively taking water away from Earth and replacing it with hydroxide, which is fairly reactive.   Likewise, comets and asteroids that hit the Earth bring water with them.   The current rate is quite small and insignificant, but 3.8 billion years ago, even after the late heavy bombardment, there might still have been frequent enough comet impacts to affect sea level over different eras.

Precise numbers aren't known - question on that here.   But if Earth loses 50,000 tons of mass per year, most of that hydrogen stripped from water, that's as much as 900,000 tons of water photo-disintegrated per year.   Over a billion years, that's 900 trillion tons of water, which sounds like a lot, but it's less than 1/10th of 1% of our ocean's mass of about 1.5 million trillion tons.

That said, when the Earth was hotter when it was young, it could have had more water in it's upper atmosphere and lost more water than 0.1% per billion years.   This estimate suggests that the Earth lost as much as 25% of it's water over the last 3.8 billion years based on studying deuterium ratio in 3.8 million year old rocks to water on Earth today.

There's also the problem of water emerging from inside the Earth.   It was recently discovered that the lower mantle is wet and there's as much water deep inside the Earth as there is in the oceans, maybe more.   How much mantle water made it's way to the surface of the Earth during the pre-cambrian era is unknown.  Some of Earth's water today likely came from inside, even though the heat of formation of the planet probably lost most of it, some (at least an ocean's worth) is still deep inside the Earth but much (most?) is thought to have come from comets and meteors during the late heavy bombardment.

  So is the rise and fall of sea level derived from the geological
  record measured relative to the adjacent land, or the center of the
  earth, or what?

Speaking strictly for the geological record, it's not directly measured, but estimated by the methods discussed above, looking at geological records of old shorelines and land that was once under water and working out an estimate.

Sea level from the center of the Earth is mostly done for modern measurements.   You can measure sea level against the land, but land can rise and fall, or it can be measured from the center of the Earth, independent of land shifting.   I don't think that's particularly relevant to your question on geological estimates of sea level.

That probably needs some cleaning up, but it's a fun subject.   I thought I'd give it a shot.


Is Oregon lake extremely pure water? If so, why? My question is,

  Is the lake shown in the YouTube video Clear Lake, Oregon extremely pure water by volume not counting dissolved air which might be about 1 in 20 by volume?

In case you didn't realize, even pure water probably can absorb a significant fraction visible light even in the region with the lowest absorbtivity. I'm guessing that lake has essentially the same absorbtion spectrum in visible light as pure water and that you pretty much cannot see more than 200 meters through water at all based on my observation of that video. I guess it's technically correct to say it's extremely pure but is not extremely clear. Since pure water itself is not completely clear, I cannot tell for sure by observation that it doesn't have a solute with colour in it.

I believe the lake shown in the YouTube video Adventure Oregon - Lost Lake draining into a giant hole is the exact same lake. I don't know that so I will specify that I'm asking about the one in the YouTube video Clear Lake, Oregon even if it's a different lake. According to the YouTube video Adventure Oregon - Lost Lake draining into a giant hole, the lost lake of Oregon is a seasonal lake. If they are the exact same lake, could the purity be caused by the drain hole? If the drain hole really is in the lowest part of the lake, could the fact that water is constantly draining and getting replaced by rain water prevent and dirt from getting stirred up and lingering in the water? In the video with the full lake, there was also grass on the floor of the lake which is a sign that the lake might be a seasonal like and therefore might be the same lake as the one in the other video. Maybe also because of the drain hole, any slight bit of the type of moss suited for water dies off after the lake drains and its floor dries so there's no moss to break off microscopic fragments into the water and make it appear green.

The visibility or "clearness" is more a matter of suspended particulates, and organic material such as algae, than of dissolved material.  For instance, runoff from glacial streams can be nearly opaque due to suspended rock flour, yet "pure" in the common sense of not having much in the way of algae &c. Conversely, some parts of the oceans can be very transparent due to lack of suspended sediment & organic matter, yet still have the same dissolved salts as other parts of the ocean.


Why do hurricanes hitting the US East Coast seem to go north once hitting land? Question says it all really. It appears that every hurricane hitting the US East Coast directs itself north once on land.

Hurricane Florence is predicted to hit North Carolina then turn toward Canada
Katrina -> Floridan and Louisiana -> Great Lakes
Dennis -> Florida -> Great Lakes

It is mostly due to the Coriolis effect (aka Coriolis Force). (Another reference here) Because of the Coriolis Effect, parcels of air (think of boxes of air) in the northern hemisphere are deflected to the right. This means that air around the subtropical ridge over the Atlantic ocean circulates clockwise.

Think of a tropical cyclone as a parcel, or box of air. It tries to complete the clockwise rotation around the subtropical high.

Now, inevitably someone will say 'Aha! I know of a storm that actually moved south.' Yes, different things can cause tropical cyclones to move in strange directions, such as the Fujiwhara Effect, other meteorological features. But by and large, the Coriolis force is the dominant cause of the curvature of the path of tropical cyclones.

It is also worth pointing out that the hurricane also has parcels of air inside of it. The Coriolis Force acts on that too, promoting rotation.