Why is ground water rising on these forest rings? I am seeking a physical explanation for this;

There is huge amount of such a Forest rings in Earth; (Link to Google Maps to one ~400 m Ring)

  They range in diameter from 30 metres to 2 kilometres, with the
  average ring measuring about 91 metres across. Over 2,000 of these
  forest rings have been documented, but scientists estimate the actual
  number is more than 8,000. Forest rings in Canada

My question relates to following observation;

  There seem to be giant electromagnetic disturbances in the soil and
  subsoil that affect not merely growth of vegetation over large areas
  but also the level of the water table: it rises “against” gravity
  within the circle.

Behind the link in the given link it's said more clearly;

  But it gets weirder: as Hamilton’s fieldwork also revealed, there is a
  measurable “bulge in the water table that occurs over the entire
  length of the forest ring with a profound dip on the ring’s outer
  edge.” For Hamilton, this effect was “beyond science fiction,” he
  remarked to the trade journal Northern Ontario Business, “it’s
  unbelievable.”

  What this means, he explained, is that “the water is being held up
  against gravity” by naturally occurring electrical fields.

And further from The Journal Ontario Business;

  Hamilton was testing an analytical technique over a Matheson gold
  deposit to determine if there was any kind of geochemical surface
  signal. To his surprise, there were signals coming through 30 to 40
  metres of glacial clay.

  “We’re thinking there’s no way metals can move through clay 10,000
  years after glaciation.”

  After ruling out transport by ground water, diffusion and gas, he
  theorized it had to have been lifted to surface on electrical fields.
  He applied the same theory to forest rings and discovered that they
  were also giant negatively charged cells.

Water does react to magnetic
field. But the needed $10T$ to make it lavitate is way too much
compared to Magnetic field earth provides; it's just $0.00005T$ and we
should be talking only some reasonable scale variations here.

QUESTION; Why is ground water rising on these forest rings?
The most obvious one would be dissolved gases. And this paper does provide information to this direction. But with closer study, the influence of the gases can be only 0.16 ppm. This means that the density change must come from water temperature. It can't come from the Ice deep below the ground. There is a measured temperature drop in the edge of the ring, but the inside outside of the ring seems to have approx. the same temperature near the soil surface.

It's hard to see how coverd ice would explain the perfect ring shape (up to 2 km in diameter!)? and the landscape is not even flat. (Pingo's formates in dried lakes/flat grounds) And why there is up to 2 meters soil depression in the annulus? Why there is negative reduction anomaly in the center of the rings? There seems to be some Ice deposits in the ring edge.

To point out the Physical problem of this; Rising ground water with 10 cm on $r=1km$; $A=3140000m2$ area needs quite huge continuous power source.

Nobody knows - yet. But one can say that these rings are too numerous and too regular in shape to be related to either kimberlites or (even more bizarrely) Oklo-type natural nuclear reactors, as some have suggested.

For what it is worth, here is my own hypothesis: The areas concerned are all periglacial in an area of abundant boulder clay. In colder analogues, particularly in Siberia and further north in Canada, such environments contain 'pingoes' aka 'hydroloaccoliths', which are frost heaves in the shape of ice lenses. See, for example, https://en.wikipedia.org/wiki/Pingo . These are feedback processes of circular ice formations which develop in permafrost tundra areas. The circles you refer to are exactly the right shape, diameter, distribution density, and geology to be 'fossil' (melted) pingoes.

Consider what happens when a pingo develops. The ground is highly crazed with fractures over a disk shaped area. If there is brackish groundwater in the area then the ice freezes as pure water, thereby partitioning more saline groundwater to the perimeter - thereby leaving a high-salinity ring of brackish water which subsequently stunts tree growth (as you observe). When the ice eventually melts the pingo collapses to appear much like the surrounding boulder clay, but with a fractured and much more porous texture. Wherever there is a confined or semi-confined aquifer - which is very common because thick layers of impervious boulder clay behave as a confining layer - there will be a tendency for groundwater to rise as artesian (non-overflowing) conditions. Hence the 'bulge' of the apparent water table, which you also observe.  If this explanation is correct then the ring would be a natural exit and pressure release point for confined groundwater, and hence for entrained methane. Methane builds up under boulder clay, especially where the clay overlies peat deposits, such that oxidizing organic matter reduces the water. Moreover, this redox contrast, between surrounding oxidized near-surface/perched groundwater, and the reduced groundwater exiting from the ring, would also influence the nutrient availability, thus contributing to the ring of stressed vegetation.

As for the change in electrical potential, that is easily explained as deriving from the contrast between normal and residual more saline groundwater. Also, if the pingo was weathered during its evolution, then there would be a difference in clay content, which would also contribute to the electrical differential. Indeed, that is to be expected when a hill (the pingo) is drained by meteoric water, taking with it any dispersive clay (another common feature of boulder clay).

So no, sorry to disappoint, but the explanation is probably just normal periglacial hydrogeology - no gold deposits involved.

The test to verify this hypothesis? It needs someone to run a traverse across such a ring, measuring the hydrostatic pressure variation (horizontal and vertical), soil salinity, and soil clay content.


Why are atmospheric BrO and ClO important to measure by satellite? The announcement Arianespace orbits two satellites – JCSAT-17 and GEO-KOMPSAT-2B – to support connectivity and environmental monitoring in Asia mentions GEO-KOMPSAT-2B which hosts the Geostationary Environmental Monitoring Spectrometer or GEMS UV/Vis (300-500 nm) imaging spectrometer for hyperspectral imaging of Earth's atmosphere.

The instrument's purpose is given as

  Ozone profile and total-column or gross profile of other species. Tracked species: BrO, NO2, O3, OClO, SO2 and aerosol

and its primary mission objectives are listed as

BrO Mole Fraction
ClO Mole Fraction
H2O Mole Fraction
HC3Br Mole Fraction
HCHO Mole Fraction

with the following as other mission objectives

HCHO Total Column
NO Mole Fraction
NO2 Total Column
NO2 Mole Fraction
O3 Mole Fraction
O3 Total Column
SO2 Mole Fraction
SO2 Total Column

I think that "Mole fraction" is a relative concentration and "Total column" is absolute?

I see that some of the species listed in the instrument's purpose are not in its primary objectives, but oh well.

Question: Why exactly are atmospheric BrO and ClO so important to measure, and measure by satellite, and what is the difference between ClO in the "objectives" and OClO in the "purpose"?

BrO and ClO significantly deplete ozone from the atmosphere.

Researchers at Harvard University state:

  It is a remarkable fact that perhaps the most important observation coupling climate forcing to UV dosage levels at the surface at mid-latitudes is the observation of high (e.g. > 10 ppmv) water vapor and low temperatures (< 210 K) with the simultaneous determination of BrO and ClO in the lower stratosphere at mid-latitudes.

Similarly, Science magazine states:

  Halogen-radical chemistry was responsible for approximately one-third of the photochemical removal of O3; reactions involving BrO account for one-half of this loss.

Additonally,

  ... where the chlorine and bromine thus released participate in the catalytic destruction of ozone.

Kinetic studies of the BrO plus ClO cross-reaction over the range T=246-314 K


What is the tectonic explanation for parallel ridges in the Arctic Ocean? Looking at a map of the underwater features of the Arctic Ocean reveals three roughly parallel ridges, separated by basins (see image below):

Image source

The three ridges, as labelled are the Alpha Ridge, Lomonosov Ridge and the Gakkel Ridge, the latter being the slow moving plate boundary between the Eurasian and North American plates as an extension of the Mid Atlantic Rift, according to the Polar Discovery page Arctic Seafloor Expedition: July 1-Aug. 10, 2007.

What is the tectonic explanation for these parallel ridges in the Arctic Ocean?

Additionally, are they in anyway linked?

The fact that these three features are parallel may be somewhat coincidental, although we can suspect that tectonic forces have influenced their morphology. The crust under the Arctic Sea is one of the least understood regimes in the world.

This is changing - whichever country can prove that their nation's continental shelf extends along one or more of these ridges can, according to the United Nations, claim subsurface oil and minerals.  Candidate countries include Russia, Canada, Norway, the USA, and Greenland/Denmark. As a result, there has been recent seismic and geological work in the area, though some of the reports are nuanced in an effort to bolster nationalistic claims.

Alpha Ridge is a volcanic ridge extension off the continent from
   Ellesmere Island, Canada.

Lomonosov Ridge seems to be ancient continental crust and is likely an
   extension of Canada's continental shelf.

Gakkel Ridge accompanies a spreading seafloor rift which extends north from the mid-Atlantic ridge. It has the slowest divergence of any mid-ocean ridge in the world (less than a centimeter a year).

Here is how the three ridges appear in cross-section:

   (Source: http://en.wikipedia.org/wiki/File:BrnBld_BeringToFram.svg)

There are two basins in the Arctic. The part closest to Europe, the Eurasian Basin, formed when the mid-Atlantic Ridge grew to the north, becoming the Gakkel Ridge. It divided a long, narrow strip of continental crust from the Barents Shelf, the Lomonosov Ridge. This action resulted in Lomonosov's parallel orientation to the Gakkel. Since the Alpha Ridge is further to the west and within the Amerasian Basin, it might be a stretch to suggest it is related to the Gakkel. It's parallel orientation is more likely an accident and in time it may rotate with respect to the other two ridges.

For an accessible and lucid description of the Arctic's tectonics, this piece by Bernard Coakley in the New York Times is quite good:  http://scientistatwork.blogs.nytimes.com/2011/09/15/northern-lights-on-the-midnight-watch.


How is ocean heat content measured? The oceans are absorbing much of the heat from climate change.

How is all of this heat measured?

The easiest way this is measured is via Argo floats. They're probes which periodically dive into the sea, and measure the ocean heat content.

This is done by calculating the formula. According to the European Environmental Agency, this formula is:

  Ocean heat content is defined as the integrated temperature change times the density of seawater, times specific heat capacity from the surface down to the deep ocean.

This could also be done manually by calcuating out the formula, and obtaining the temperature of the seawater by using a device such as a Nansen Bottle.


How are the banded-iron-formation iron-ores formed? Many of the richest and purest iron ores are found in so called banded iron formations, cm thick magnetite or hematite layers intermixed with iron poor rock layers. Since these are usually of pre-Cambrian age, the processes involved seem to preclude modern day environments.

A few elements to complement @Siv answer, and some alternatives hypotheses:

Originally the idea was that the Fe2+ oxidation into Fe3+ that lead to the formation of the BIF ("banded iron formations") was an indirect consequence of the increased atmospheric pO2 caused by the photosynthetic activity of, then freshly appeared, cyanobacteria (see e. g. Cloud 1973  which, along with Cloud 1968, are i think the first occurrence in the literature of such an idea).

Later, the idea that the cause of the iron oxidation was linked to a specific metabolic reaction involved in anoxygenic photosynthesis (i. e. a different way of fixing CO2 that does not create O2) in bacteria was also introduced (Hartman 1984; Konhauser et al. 2005).

Another possibility invoked by Holm 1989 is the active oxidation of Fe2+ by "chemolithoautotrophic" bacteria (using it directly as energy source).

Finally, the only (as far as I can see) non-bacterial hypothesis on the BIF formation is that of photo-oxidation (Braterman et al. 1983): the oxidation and precipitation of Fe2+ in Fe3+ being indeed possible without oxygen, in strongly acid conditions with a little help from UV photons.

References:
Braterman P. S., Cairns-Smith A. G., Sloper R. W., 1983. Photo-oxidation of hydrated Fe2+ – significance for banded iron formations. Nature, 303: 163-164.
Cloud P., 1968. Atmospheric and hydrospheric evolution on the primitive earth. Science, 160, 729–736.
Cloud P., 1973. Paleoecological Significance of the Banded Iron-Formation. Economic Geology and the Bulletin of the Society of Economic Geologists, 68: 1135-1143.
Hartman H., 1984. The evolution of photosynthesis and microbial mats: A speculation on the banded iron formations. In Y. Cohen et al. (Eds), Microbial  Mats: Stromatolites, Alan Liss Inc. (New York): 449–453.
Holm N. G., 1989. The 13C/12C ratios of siderite and organic matter of a modern metalliferous hydrothermal sediment and their implications for banded iron formations. Chemical Geology, 77: 41-45.
Konhauser K. O., Newman D. K., Kappler A., 2005. The potential signiﬁcance of microbial Fe(III) reduction during deposition of Precambrian banded iron formations. Geobiology, 3, 167–177.


Why is the sky bluer in winter than in summer? I don't know why, but I have noticed my whole life that the sky's blue color seems saturated in winter and sort of pale, milky, and washed out in the summer. Does it have to do with the angle of the sun during seasons and/or the absolute humidity?

The angle of the sun and humidity, indeed have a major effect on the color of the sky. To start, when there is a higher humidity level there is obviously a greater quantity of water vapor in the atmosphere. This leads to more of what is called Mie scattering. Mie scattering in this scenario is when the water vapor and water droplets direct more blue spectrum of light back into space causing you to see a smaller portion then what is possible with less scattering. Depending on where you live the seasons vary for when there is the least amount of humidity.

Now secondly, if you live between 30-60 degrees North or South, the suns angle changes enough, that the spectrum of light is affected. When the sun is closer to the horizon, the light is traveling through more atmosphere than it would if the sun were directly above. This leads to Rayleigh scattering, which end and end directs more blue light to your eyes.


How to calculate the solar radiation at any place, any time The solar radiation is one of the important factors controlling the formation of $O_3$, and thereby impacting the levels of various secondary species in the atmosphere.

However, in the campaign of ambient $PM_{2.5}$ sampling, I don't have the instrument to acquire the actual solar radiation data. Since the solar radiation can be calculated mainly by the altitude degree of the sun, I turned to find a way to calculate the ideal values in clean sky condition.

I found that pysolar is a potential tool to tackle this kind of issue.  By simply defining the location(Lon, Lat), and the date time, the solar radiation in the unit of $W/m^2$ can be generated.

  However, the output result here seems to be strange.

Here is an example using Python 3.4:

# Noted that the package can only be implemented in Python 3.4 environment
from pysolar.solar import *
import datetime

# define the location (Beijing, China)
lat, lon = 39.9075, 116.39723

# generate the time series dataset of the solar radiation
start = datetime.datetime(2018, 1, 1, 8, 0, 0, 0, tzinfo=datetime.timezone.utc)

solar_data = []
for i in range(0,24*90,1): # 24 hours x 90 days
    date = start + pd.to_timedelta(1,'H')
    altitude_deg = get_altitude(lat, lon, date)
    solar_data.append(radiation.get_radiation_direct(date, altitude_deg))

solar_ = pd.Dataframe([])
solar_['value] = solar_data

# Plotting
## Before plotting, I found there are a lot of extreme values with the radiation larger than  10e5. I don't know the reasons why they came up, and how to delete those data by conditions.

solar_.loc[solar_.value>5000, 'value'] = np.nan
plt.plot(solar_.value)

The result seems to be incorrect. In my opinion, the solar radiation should present a clear diurnal pattern with seasonal heterogeneity.

How to explain the bizarre results? Or is there any better solution for the solar radiation data if the monitoring equipment is unavailable.

Any comments or suggestions would be appreciated.

PS: I added the result of altitude degree   the same period to response the comment of BarocliniCplusplus

Look at the pysolar docs (http://pysolar.readthedocs.io/en/latest/) under "Estimate of clear sky radiation". The algorithm does not return zeros at night, but instead just plugs those numbers straight in, giving nonsensical values. Filter the results so that if altitude_deg < 0, the radiation is 0. An example just using pysolar, datetime, and pyplot (I don't use pandas, so I can't comment on that) and lists looks like:
import datetime
import matplotlib.pyplot as plt
import pysolar
lat, lon = 39.9075, 116.39723  # Beijing, China
timezone = datetime.timezone(datetime.timedelta(hours=8))  # 0800 UTC
start = datetime.datetime(2018,1,1,tzinfo=timezone)  # 1 Jan 2018

# Calculate radiation every hour for 90 days
nhr = 24*90
dates, altitudes_deg, radiations = list(), list(), list()
for ihr in range(nhr):
    date = start + datetime.timedelta(hours=ihr)
    altitude_deg = pysolar.solar.get_altitude(lat,lon,date)
    if altitude_deg <= 0:
        radiation = 0.
    else:
        radiation = pysolar.radiation.get_radiation_direct(date,altitude_deg)
    dates.append(date)
    altitudes_deg.append(altitude_deg)
    radiations.append(radiation)

days = [ihr/24 for ihr in range(nhr)]
fig, axs = plt.subplots(nrows=2,ncols=1,sharex=True)
axs[0].plot(days,altitudes_deg)
axs[0].set_title('Solar altitude, degrees')
axs[1].plot(days,radiations)
axs[1].set_title('Solar radiation, W/m2')
axs[1].set_xlabel('Days since ' + start.strftime('%Y/%m/%d %H:%M UTC'))
plt.show()


Are weather forecast models more accurate for either high or low temperatures? The other day our low temperature for the day was ~10 degrees F below our forecast low.  I've noticed this before in the winter, especially when temperatures start to go below 0 degrees F (-18 degrees C).  This made me wonder if the models used to forecast high and low temperature are different, and if so is one indeed more accurate?  Conversely, if the same model is used, is it as accurate for both high and low temperatures?

I was able to find one student project from Dartmouth College in which a statistical analysis of forecast high and low temperatures were compared from three five years sets (1970-4, 1980-4, and 1990-4) of data from 15 different United States cities representing different influences such as latitude, water, and land influences.  One of the findings of this dataset of 5,269 records was that the forecasts where more accurate in the summer than in the fall and winter.  This seems to hint that warmer temperatures are forecasted more accurately than colder temperatures, at least on a seasonal basis.  I'm hoping there's more information out there that can either confirm or deny this conclusion without the seasonal bias.

There are two ways to answer your question: the first would be by verifying historical forecast data (calculating the difference to observed temperatures) and looking into a temperature dependency of these errors. This would certainly be doable - but in this context on Stackexchange not.
So I suppose you refer to a general, more physically interpretable explanation what the difference in forecasting higher or lower temperatures is.
Even though it makes a difference for physical processes like radiation and evaporation if temperatures are high or low, the characteristics stay the same - more explicitly said:
Temperature differences matter more than absolute temperatures!
For example:

The net radiation (budget) is proportional to the difference of soil and atmospheric temperature (each to the fourth power).

Deeper layers of soil keep the surface warm by transporting heat (also proportional to the temperature difference).

and so on...

But there is a significant difference in the active physical processes:
At daytime (Tmax), the near surface air is (mostly) coupled to the temperature of higher layers of air by turbulence. On a sunny summerday, the surface air can not get significantly warmer than the air above because if it gets warmer, the air rises and cooler air from above cools the surface layer. In this way, the surface air temperature is 'tied down' so that it can not reach extrordinary temperatures without also heating up a say 1500 m boundary layer of air.
If the surface air is cooler than the air above it gets decoupled from the temperatures above - turbulence is reduced, and theoretically the temperatures could drop a looong way down, until the incoming (longwave) radiation from the atmosphere (say hi to greenhouse gases) stops this temperature drop. The equilibrium temperature depends mostly on the amount of water vapor above our heads -> warmer in the tropics, cooler nights in polar regions. But the equilibrium is practically never reached. In most cases it is a dynamic thing with  ground heat flux and sporadic wind gusts - which are of very local effect.
Conclusion
Comparing these two cases one can see that the Tmax is more homogenously distributed in space because it mostly depends on the airmass. Minimum temperatures can be very different even for close locations because it really depends on your surrounding: trees, buildings, ridges. You can see the lowest Tmin at high altitude locations which are not exposed to wind gusts (sinkholes) which are covered by snow (isolated from soil heat).
So by analyzing a forecast error dataset, you would most likely see that Tmax are more accurately forecast.


How close to the magnetic poles will a compass be accurate? So the Earth has a giant magnetic field we use to determine direction. The field roughly looks like a magnetic dipole, but because the field is generated by a turbulent liquid dynamo near the Earth's core, it's not a perfect dipole.

This leads me to believe that as you approach the magnetic north or south poles, your compass reading will become increasingly vague, and that there's probably a finite region near the pole where the compass direction rather randomly points some direction other than the pole itself.

Additionally, as you near the pole of a perfect dipole, the component of the magnetic field tangent to the surface approaches a magnitude of zero. Because real-world compasses have friction, imperfect magnets, and so forth, there's surely some minimum field strength required to accurately move the compass magnet.

Finally, I know that the pole has daily cycles as well as long-term movements. My guess is the daily cycles can be predicted with some kind of almanac or equation, and that travelers near the pole could receive periodic updates as to the center of the daily cycles so they could adjust their local declination accordingly. Still, there would be some kind of precision error here that might be significant.

Between the three effects above (and possibly others I don't know about), I'm guessing there's a real-world limit on how close you can get to the exact magnetic pole before a real-world compass can no longer be trusted.

How close can we get to the magnetic pole and still use a compass to determine direction?

To narrow the scope of the question, I'm thinking of a standard compass I can pick up at Walmart for like $10 (say, this one). However, answers regarding high-end compasses and very low-end compasses (like, a magnetized needle through a cork floating in water) would also be appreciated.

Additionally, my question relates to humans using compasses for navigation, so if the answer is less than a few hundred meters, that's close enough to "right on the pole" for my purposes. At that point, you could simply look at the building or other landmark you're trying to find. Conversely, if the answer is several hundred miles, that would make it impossible to use traditional compass-based navigation between settlements near the magnetic pole.

Regions where the strength of the horizontal component (H) of the magnetic field is small (i.e. where the field is close to vertical near the magnetic poles) define where a compass won't work reliably.

For example where H drops below 5000nT is considered unreliable for values of magnetic declination as per the error calculations in the World Magnetic Model 2015 report. I've seen aviation charts (of which I can't find an example) where 6000nT (also based on the WMM as that's the industry standard there too) is used to define where another navigation aid should be take preference.

You can get an idea of the geographic distances involved from this map of the 2015 horizontal field intensity over the northern hemisphere. The distance of a given field strength value to the pole isn't a fixed value as the field isn't exactly a dipole, so the south pole map looks quite different, but you get a realistic idea at least. Something like within 2,500km in the North, and a few hundred km in the South.

As @Tactopoda pointed out, declination can be very large within thousands of km of a magnetic pole, and the annual rate of change of H is also much greater than elsewhere, hence why a compass isn't very reliable, even where it can give a consistent reading.


Biogenic origin of authigenic zeolites Bohrmann et al. 1989 advanced the idea that the silicate phase from some clinoptilolites come from the diagenetic degradation of biogenic opal (from radiolarians in that case but presumably also other siliceous microfossils).

If this hypothesis is still regarded as valid, is clinoptilolite the only kind of authigenic zeolite that can be traced to biogenic opal?

Has any work been done in that domain since this paper?

Source:
Bohrmann, G., Stein, R., Faugères, J.-C., 1989. Authigenic  zeolites  and their  relation  to  silica  diagenesis  in ODP  Site  661 sediments  (Leg  108,  Eastern Equatorial  Atlantic). Geologische Rundschau, 78(3): 779-792.

Yes, there have been recent research in this field.

In the article Oceanic minerals: Their origin, nature of their environment,
and significance (Kastner, 1999), who asserts that

  The zeolites phillipsite and analcime mostly reflect on
  diagenesis of volcanic matter; clinoptilote and heulandite occur in Si-rich
  diagenetic environments.

and confirm that

  In addition to diagenetic opal-CT and quartz that
  form from the dissolution of biogenic opal-A, other common
  authigenic alumino-silicate minerals are smectites and zeolites.

This is further confirmed by a 2007 paper Clinoptilolite as a new proxy of enhanced biogenic silica productivity in lower Miocene carbonate sediments of the Bahamas platform: Isotopic and thermodynamic evidence (Karpoff et al) which determined that

  Seawater–rock modeling specifies that clinoptilolite precipitates from the dissolution of biogenic silica, which reacts with clay minerals. The amount of silica (opal-A) involved in the reaction has to be significant enough, at least 10 wt.%, to account for the observed content of clinoptilolite occurring at the most zeolite-rich level. Modeling also shows that the observed amount of clinoptilolite (∼ 19%) reflects an in situ and short-term reaction due to the high reactivity of primary biogenic silica (opal-A) until its complete depletion.


How to add scale in DSLR plus microscope set up by default? We have an Axioscope microscope and planning to install a Nikon D5300 camera on top of it. The software I looked up, is DigiCam Control. The downside is we cannot add scale by default. The scale has to be calibrated for each slide. We capture lots of photos, so calibrating the scale each time we change the sample is waste of time. Does anybody have any idea regarding this issue?

Select the objectives you want to use on your microscope altogether with your camera.  If the camera is not a permanent installation, ensure that the mount reliably establishes again and again the same position and alignment in respect to the optical axis of the microscope.

See if your group has a stage micrometer, a slide with fine regular markings:

(credit)
If not purchased altogether with the microscope (one other source), or lost during a move of the group you work in, see if an other group in your school active in microscopy may lend you one.  It may be in geology, but equally in (analytical) chemistry, biology, histology, (laser) physics / optics, etc.

Identify a reliable protocol to get hold of the images recorded by your camera to be fed into a suitable software e.g., ImageJ / Fiji.

Take a good photograph with your camera mounted on the microscope observing the micrometer plate, starting with a low magnification.  For once, you have to count the pixels to calibrate profiles for a given combination of objective, inner optics, and mounted sensor / camera. But today, you may get assistance by the software's plugin (example, documentation, tutorial video).


Volcanoes in the Great Barrier Reef Was there ever at any point in time a volcano in the great barrier reef? I thought atolls develop from volcanic islands, and the coral grow around them.

Australia's Institute of Marine Science webpage How the Great Barrier Reef was formed is the result of the flooding of the former coastal plain when sea levels were lower.  A further explanation from the website states:

  The coastal plain included river valleys and small and large hills. Corals tended to grow best on hills because they were where waves broke and the water was most turbulent. Thus, although corals probably grew on any available hard shallow surface on the flooding coastal plain, reefs tended to form where there were hills.

A diagram of the formation is shown below:

Image source

So, not the result of volcanoes, but rather the after effects of coastal plain inundation.


Why did the Australian bushfires cause pitch darkness during the daytime? Saturday 4th January was truly an extroadinary and terrible day for the south-east corner of Australia. Skies turned pitch black at around 3-5 pm, when normally these areas would be in daylight. I have never been aware of this sort of phenomenon. Is it possible that thick smoke alone could have caused this, or was it larger particles such as burnt leaves and bark, picked up by strong updraughts from pyrocumulus clouds? It is worth noting that this occurred right before a cold front passed through the area, bringing southerly winds, and that pyrocumulus clouds had formed, and lightning was being generated from them.

It's a combination of both the density and amount of smoke in the air and ash produced by the fire.

The thing about cold fronts and bush fires is they make the conditions for fire worse by pushing hot air in front of them. They have been blamed for the severity of the bush fires in Victoria in 2009, 1983 and 1939.


Earth and moon have different mantle compositions. Is this a fatal flaw in the 'Giant Impact hypothesis'? Deep impact ejecta on the moon seem to indicate that the moon's mantle is predominantly 'low-calcium pyroxene' (recent letter to Nature), whereas the Earth's mantle (or at least the upper mantle) is dominantly olivine with only ~15% pyroxenes. So how can this discrepancy arise if the Earth and moon have a common origin? The only possibility I can think of is if partial fractionation of magnesium silicates actually took place in space, before falling to either Earth or moon, with the slightly denser olivine falling to the higher gravity of Earth, and less dense pyroxene falling to the lower gravity proto-moon. Is this possible? Is there any isotopic evidence of Earth-moon mantle commonality?

I highly recommend this blog article from the Planetary Society. It is from 2012 but I believe the science is still sound. The author herself, has received recognition for her contribution to communicating space science to the public (She has an asteroid named after her!!)

It doesn't address your question about if there is a flaw in the giant impact hypothesis through an isotopic analysis, but rather through a gravity anomaly analysis from the GRAIL Mission.

Isostasy, gravity, and the Moon: an explainer of the first results of the GRAIL mission. Written by Emily Lakdawalla, 11 December 2012

The article starts off by giving some information on how gravity anomalies are formed and measured, before delving into the main arguments.

In Summary (all mistakes are mine), using various analysis's of the gravity anomalies, resulting in 3 further scientific papers linked in the article, the GRAIL mission has determined that the Moon has a highly fractured and highly mixed crust. The crust is alot thinner than previously thought and in some places the crust is nearly or even 0 km deep, allowing mantle minerals to be exposed on the surface. The unexpected porous nature of the crust supports the Earth/Moon common origin, whereas before there was a mismatch in the assumed numbers giving some doubt to the giant impact hypothesis.

The article then finishes off by mentioning an existing theory on how the moon could have formed while still creating the observed features we can see today.

About halfway through the article, after discussing Airy and Pratt Isostasy, the article starts to mention the observed results. When looking at the Bouguer gravity of the Moon,

  Now, the Moon should have local, small-scale variations in crustal density due to local geology; the fact that the variations are small and smooth means (Zuber argued while presenting these results) that impact cratering has completely battered, bashed, fragmented, mixed, and remixed the upper couple of kilometers of the crust, totally homogenizing it. Previous maps of lunar gravity have not had high enough detail to see this beautiful match between topography and gravity; so this is a new GRAIL result.

a little further on discussing some more results about the density of the moon surface,

  There is one big very surprising thing about this map. The average density is 2550 kilograms per cubic meter. This is much, much lower than what has been assumed for lunar crust; in fact, it's lower than the density of granite. We know what the highlands crust is made of, we have samples of it: the density of the minerals that makes up the crust is around 2800-2900 kilograms per cubic meter. For the Moon's density to be so low, Wieczorek says, it must be very porous, fractured and busted up to give it about 12% void space, to a depth of several kilometers below the surface. This is an important GRAIL result. The mission has given us X-ray vision to see that the Moon's crust is absolutely shattered from the surface for thousands of meters down. In places where the crust is very thin, even the uppermost mantle may be fractured and porous.

Here is where the article starts discussing the mantle minerals, especially Olivine which you mentioned. (emphasis is mine)

  This map shows crustal thickness is near zero under a few of the impact basins (particularly Crisium and Moscoviense) and some of the deepest craters inside the south pole-Aitken basin (Humboldtianum, Apollo, and Poincaré). And the crust reaches a high of 60 kilometers on the farside. Kaguya compositional data support the GRAIL conclusions. There's evidence for the mantle mineral olivine being exposed in precisely those places where GRAIL sees the thinnest crust: Crisium, Moscoviense, and Humboldtianum.

  The average crustal thickness that Wieczorek and coworkers calculated, 34-43 kilometers, is much lower than has previously been assumed. Why is that important? Because when you work out the math to figure out what the bulk composition of the Moon is, given this thinner crust, you wind up with numbers for the abundance of aluminum that are a much better match to Earth's aluminum abundance than they were before. Previously, an apparent compositional mismatch had been a problem dogging the giant impact hypothesis for the Moon's formation. The GRAIL result makes for a compositional match.

Near the end of the article, The article mentions Sean Solomon's idea on how the moon could have formed.

  Andrews-Hanna pointed out that some theorists have predicted exactly this situation. The paper he cites was by Sean Solomon, principal investigator on the MESSENGER Mercury mission, who was trying to explain how Mercury could have wrinkle ridges caused by global contraction if the Moon does not.

  If you condense the Moon from a ring of debris orbiting Earth following a collision, the first nucleus of the Moon will actually be quite cold. As it grows, the increasing energy of the impacts of stuff onto the proto-Moon would make the Moon's mantle hotter than its deep interior; you could wind up with a cool, solid center surrounded by a hot, liquid mantle. The heat from the mantle would take time to propagate into the interior; as it did, the warming center of the Moon would expand, producing exactly the kind of global extensional stresses that could make this set of dikes. The model has this expansion happening at the correct time, too: before the Moon was 500 million years old, which would be before the end of the basin-forming impacts.

I hope I actually understood the article correctly and that it helped answer your question. Albeit through a different route.


Will the Southern Ocean act as a net source or sink for atmospheric $\ce{CO2}$ in the future? Some estimates claim that currently about one third of current human annual emissions of $\ce{CO2}$ are absorbed by the oceans. Some authors have calculated that about half of the global ocean total absorption occurs in the Southern Ocean. They also claim that:

  the ocean $\ce{CO2}$ sink intensity has been weakening for several decades and has changed from a net sink to a net source since 2005

Considering the potential changes in ocean circulation and biological activity associated with climate change, can we expect the Southern Ocean to remain as such an important sink or are we moving toward a regime change that will lead to the ocean becoming a source of $\ce{CO2}$?

I think you may have misunderstood the abstract of the paper, which says:

  Various human activities, including fossil fuel combustion and forest
  clearing, emit about eight petagrams (or billion tons) of carbon in
  the form of CO2 into the atmosphere annually. The global ocean absorbs
  about two petagrams of CO2, and about a half of that amount is
  absorbed by the Southern Ocean south of 30°S, thus slowing the rapid
  accumulation of CO2 in the atmosphere. Partial pressure of CO2 (pCO2)
  is a measure of the chemical driving force for the CO2 exchange
  between the ocean and the atmosphere. This paper discusses its space
  and time distribution over the Southern Ocean. The major sink zone for
  atmospheric CO2 is located in a latitude belt between 30°S and 50°S,
  where the biological utilization of CO2 and cooling of warm
  subtropical waters flowing southward produce low seawater pCO2.

Note that most of the "half of the global ocean total absorption" occurs in a band between 30°S and 50°S.

  Strong
  winds in this zone also enhance the ocean's uptake. Although the
  source-sink conditions vary over a wide range through the seasons in
  the areas south of 50°S, this zone is a small sink on an annual
  average. Winter observations show that surface water pCO2 values in
  the source region for Antarctic Intermediate Water have increased at a
  rate faster than the atmospheric increase rate, suggesting that the
  ocean CO2 sink intensity has been weakening for several decades and
  has changed from a net sink to a net source since 2005. The results of
  ocean general circulation-biogeochemistry model studies are found to
  be consistent with the observations.*

The "net sink to a net source since 2005" appears to relate to this area south of 50°S, which was only a small sink to begin with.  This suggests that the southern ocean as a whole is still a strong carbon sink.  As the evidence for an increase in the airborne fraction increasing is currently equivocal, this suggests that the natural carbon sinks (including the southern ocean) is still strengthening in response to increasing atmospheric concentrations.

Note the conclusion of the paper talks of the 30°S and 50°S being a sink in the present tense, which would be inappropriate if it had become a net source since 2005.


What will be the temperature on Earth when Sun finishes its main sequence? We know that presently Sun is 4.5 billion years into its main sequence. It has another 5 billion years before it enters the Red Giant phase. We also know that Sun's luminosity increases by 10% every billion years during the main sequence. I am interested in finding the temperature rise as we approach the end of main sequence. I got two different values for temperature on Earth.

Wikipedia entry says that temperature on Earth would be 422 k in 2.8 billion years. However, if we use the formula for effective temperature as discussed in this answer
https://earthscience.stackexchange.com/a/4274/15299 and L = 1.8 then, the temperature on Earth would be 330K. Also in this book, the author does the same calculations on page 255.

Answers will be different because they must be tied to a model of solar evolution, and all models are a bit different.

So to answer your question we have to select a model. A pretty standard and trusted one, is the one used in the paper Stellar evolution models for Z = 0.0001 to 0.03. Where Z stands for the metalicity of the star, that for the Sun they indicate would be 0.0188.

In figure 2, they show the trajectory of a star like the sun in the H-R diagram (look for the line labeled "1.0").

The data output of this model is available at the VizieR catalog. I just downloaded the data for starts of one solar mass and Z=0.02 (like the Sun), and computed the effective temperature of Earth using the formula in the linked question

$\Large \frac{T}{T_0}=\left(\frac{L}{L_0}\right)^{\frac{1}{4}}$

Using a current effective temperature $T_0$ of -19°C (you will find values between -18 and -21°C), we get that the plot of Luminosity and temperature versus time looks like this

And given that you are interested in specific values here is some tabulated data including also the solar radius. Note that most of these points are linear interpolations of the original data, that had only six points in this age range.

Age         Radius      Lumin.  Temperature
[Billion    [solar      [Solar  [°C]
 years]     radius]     Lumin.]
0.00        0.89        0.7     -41.4
0.25        0.90        0.7     -40.2
0.50        0.91        0.7     -39.0
0.75        0.91        0.7     -37.8
1.00        0.92        0.8     -36.6
1.25        0.93        0.8     -35.4
1.50        0.94        0.8     -34.2
1.75        0.95        0.8     -32.9
2.00        0.95        0.8     -31.7
2.25        0.96        0.8     -30.4
2.50        0.97        0.8     -29.2
2.75        0.98        0.9     -27.9
3.00        0.99        0.9     -26.7
3.25        1.00        0.9     -25.4
3.50        1.00        0.9     -24.1
3.75        1.01        0.9     -22.8
4.00        1.02        1.0     -21.5
4.25        1.03        1.0     -20.2
4.50        1.04        1.0     -18.9
4.75        1.05        1.0     -17.6
5.00        1.06        1.0     -16.3
5.25        1.07        1.1     -15.0
5.50        1.08        1.1     -13.7
5.75        1.08        1.1     -12.3
6.00        1.09        1.1     -11.0
6.25        1.10        1.2     -9.6
6.50        1.11        1.2     -8.3
6.75        1.12        1.2     -6.9
7.00        1.13        1.2     -5.5
7.25        1.14        1.3     -4.1
7.50        1.15        1.3     -2.8
7.75        1.16        1.3     -1.4
8.00        1.17        1.3     0.0
8.25        1.18        1.4     1.4
8.50        1.19        1.4     2.9
8.75        1.20        1.4     4.3
9.00        1.21        1.4     5.7
9.25        1.22        1.5     7.2
9.50        1.26        1.5     9.2
9.75        1.32        1.6     11.9
10.00       1.38        1.6     14.7
10.25       1.44        1.7     17.5
10.50       1.51        1.8     20.3
10.75       1.58        1.8     23.1
11.00       1.66        1.9     25.9
11.25       1.74        2.0     28.8
11.50       1.82        2.1     31.7
11.75       1.90        2.2     34.7
12.00       2.40        3.1     65.0
12.25       4.08        7.8     151.9
12.50       6.94        19.6    261.2
12.75       11.68       57.8    427.2

Note that you can only know the effective temperature, the actual temperature will depend on the strength of the greenhouse effect, and modeling that is a whole new problem with huge uncertainties.

According to this model, the terminal age main sequence of the Sun would be 9.38 Billion years, and according to the data above, the effective temperature then would be 8.2 °C (281 K), that's 27.2 °C hotter than today.


Precipitation Totals past days online? I am looking for a website that can I look for to check and see the precipitation totals for past days..

I go to this site : https://www.cocorahs.org/ . It lacks in some areas where I live in the rural areas...

Are there sites that can I find that are hard to find areas like where I live ?

Location is Pueblo West, Colorado. There are some areas that received totals in Pueblo.

I have gone to The Weather Channel , WU, etc...but no luck.

One of the best sites I know of for this type of analysis is the National Weather Service’s precipitation analysis site, which combines radar data, gauge observations, and satellite data to make an informed analysis over the entire country, not just where there are rain gauges.

You can use the controls below the map to choose day(s) for which you’d like to see the precipitation analysis, and it looks like they have archived data going back to 2005. I don’t know offhand if you can quickly get exact totals from the site, but it should be enough for a rough idea.

And if you’re more specifically interested in snow totals (instead of liquid precipitation), there’s also another site from the NWS dedicated to snowfall analyses.


Is there a defined reference period for the COP21 agreement? In December, the the vast part of the world community has agreed on the tackling of climate change. This was the result of the 2015 United Nations Climate Change Conference, commonly abbreviated to COP 21 (https://en.wikipedia.org/wiki/2015_United_Nations_Climate_Change_Conference).

All media have quoted the goal to stay below 2.0°C and that the world community is even aiming for a global warming change of less than 1.5°C. However, I could not find much information on the reference period. Some time ago I've read about the period 1961 to 1990; Wikipedia states (without reference) that it's compared to pre-industrial levels. Does anyone have further information (with references) on the question, what the reference period for the COP21 agreement is?

It's relative to the immediately pre-industrial years.

As per the press-release from the UNFCCC on COP21:

  The universal agreement’s main aim is to keep a global temperature rise this century well below 2 degrees Celsius and to drive efforts to limit the temperature increase even further to 1.5 degrees Celsius above pre-industrial levels.


Magma resultant from group 1 and group 2 elements? I was recently speaking with a geology professor over lunch at a university who has a theory that I've never heard before.  His postulation was quite compelling and I was hoping to do a little digging to see if anyone else has heard of such a theory with any supporting evidence.  Apparently this fellow is onto quite a discovery, but is not yet ready to release his findings.  Quite a bit of the discussion was simply over my head since I have never really studied geology in depth.

He sets forth that magma is not actually created from heat / pressure buildup, etc., but rather that it is generated from a catalytic reaction from massive interactions of water with large group 1 and group 2 metal pockets or clusters within the earth's crust.

He further explained how the water enters into these pockets via various fissures both from our oceans and other bodies of water (noting some study from last year where researchers found incredible volumes of water 700 kilometers underground).  One side note was regarding the contents of magmatic rocks being surprisingly high in alkali metals, etc.

As I noted, it was quite compelling, but I was out of my depth and I was curious as to whether others have heard such theories or seen such data before as I would quite like to understand this topic a bit better.

So let's break it down part by part:

  He sets forth that magma is not actually created from heat / pressure buildup, etc.

There is not a single mechanism for magma formation in the Earth. Magma can form by heating, decompression, infiltration of fluids (such as water), fluxing (by light elements e.g. B, F, P etc) and more. These are all well established methods for magma formation, with an immense amount of evidence. This evidence includes independent observations from seismology, geochemistry, fluid mechanics, and probably most important - experimental simulation of these processes.

  it is generated from a catalytic reaction from massive interactions of water with large group 1 and group 2 metal pockets or clusters within the earth's crust.

By "metal pockets" I mean that you mean metals with valence 0 - i.e. in the metallic state and not bound with other minerals. This is simply not true - especially for group 1 and 2 metals. These metals are highly reactive. Just search online for videos of "sodium party". The Earth's mantle has abundant oxygen in it (bound in silicates) and any group 1 or 2 metal will simply not exist as a metal. Even if for some obscure reason it would happen, where are the magmas containing these metal (more than they occur in magmas on a natural basis)? This simply doesn't make any sense.

  He further explained how the water enters into these pockets via
  various fissures both from our oceans and other bodies of water
  (noting some study from last year where researchers found incredible
  volumes of water 700 kilometers underground).

First of all, the chemical and physical behaviour of water is completely different when you compare ocean floor settings and the deep mantle. Water may flow in fissures under the ocean, but once you get to several 10s of kilometres deep, the rocks become ductile and water can no longer flow in cracks and fissures. Regarding last year discovery of water in the mantle - this is really a sad story of poor science communication. What was actually discovered was that a certain mineral can contain water in its crystal structure. It's still a solid mineral and still a rock. Same like the water in concrete - it's not actually liquid water. See these two questions for more info:

What are the implications of the recent discovery that huge oceans exist close to the mantle of the Earth?

Do ringwoodite minerals point to an "ocean's worth" of water, or a true subterranean ocean?

  One side note was regarding the contents of magmatic rocks being surprisingly high in alkali metals, etc.

Most magmatic rocks contain a perfectly reasonable amounts of alkali metals. There are some rocks that have high alkali contents (and they have funny names too!), but this is not something that requires a different explanation from what is known so far from experiments and other studies. Yes, there are rocks with abnormally high alkali contents, and there is still research going on in that subject.

  but I was out of my depth

I think this is the key word in here actually. Perhaps that professor was "dumbing down" his ideas to make it more accessible? This occasionally happens with us scientists, and in a lot of cases the listener simply understands something completely different from what the scientist meant. Another example of poor science communication, unfortunately.


Does wind chill work in deserts? Wind chill works by removing the layer of heated air around your body. However in a hot area, say a desert, wouldn't the air around be hotter than your body or at least much closer to it than cold air? In that case, how much would wind chill actually affect your temperature loss?

As you state, wind chill "is the cooling of a body due to the passing-flow of lower temperature air.

Because of this, wind chill only occurs when then air had capacity to absorb heat from a body - thus chilling the body. The capacity of air to absorb heat from a body is dependent on the temperature difference between the air and the body, and the humidity of the air.

In determining the ability of the air to absorb heat , the wet bulb temperature must be used, in conjunction with the dry bulb. Wind chill and [heat index] (https://en.wikipedia.org/wiki/Heat_index) are related.

In a hot environment, such as a very hot day in a desert, a wind chill factor usually will usually not exist. Under such conditions is it possible to a body to over heat and experience heat stress and hyperthermia, which can lead to death. Also, one has to be careful so that wind burn doesn't occur.


How old are Chile's fjords? Do we have any knowledge about the age of Chile's fjords, more specifically, those found near the Northern Patagonian Ice Field?

Is it reasonable to conclude that they were formed in Quaternary given the fact that there exist glaciers there at this point in time?

The Quaternary is definitely a good guess. But it is difficult to answer your question because the "age of a fjord" is a rather ambiguous concept.
Also, I'll asume you are interested in the bedrock topography associated  to the fjords, and not only the sea inlets (as in that case they would have formed very recently, just when the glaciers receded enough to allow the ocean water to take their place). With that said let's try to answer the question:

The fjords of western Patagonia are a feature created by the Pleistocene glaciations, therefore you can definitely say that the fjords as a feature of the landscape were formed during the Quaternary. However, they are in constant evolution, so you can arguably also say that the fjords as you see them today, were formed today.

Glacier erosion rates in Patagonia range roughly from a few tenths of millimeters to a few centimeters per year. Faster rates probably happening at the edges of the ice sheets were glacier basal sliding velocities are higher. Long term averages (~10 ka) are probably between 0.5 mm/yr and 1 mm/yr, meaning that in the 2.6 Ma of the Quaternary you would erode just about one to two kilometers. As some fjords can be much deeper than that (when measured from the mountain tops), it is clear that the fjords as a geographical feature are not in steady state, and they are now more dramatic than ever throughout the Quaternary.

Erosion rates measured in outlet glaciers in Patagonia and other areas in different timescales. From figure 2.a in "The relative efficacy of fluvial and glacial erosion over modern to orogenic timescales" 2009, Nature Geoscience 2(9):644-647.

The reason that explain why Fjords can become deeper than that one kilometer estimate, is the concentrated erosión in outlet glaciers at the edge of the ice sheet. For example, the most visited glacier in the Northern Patagonian Icefield: the San Rafael glacier, show erosion rates of 0.83 mm/year. And as shown in the figure above, outlet glaciers can erode up to ~5 cm/yr at shorter timescales.

Sumarizing:

Northern Patagonian Ice Field's fjords started to form with the first Pleistocene glaciation at the begin of the Quaternary about 2.6 million years ago, but they have become deeper after each successive glaciation and they are still forming today. Current glaciers are eroding their bedrock at rates on the order of one to a few centimeters per year.


Origin of Serious Wildfires At a very rough estimate, what proportion of wildfires are caused by natural events like lightning? I am absolutely sure that in Europe, where there are often wildfires, the sun is never hot enough to set fire to vegetation directly, though it obviously makes things tinder dry and easily combustible. The broken bottle theory has been disproved. Experiments involving broken glass among highly combustible straw or hay were unsuccessful in causing combustion, though manual focussing of the suns rays with the lens-shaped bottom of a bottle were on rare occasions and with much difficulty successful. Although lightning undoubtedly causes the occasional wildfire, the majority have no connection with lightning. It should also be remembered that lightning is usually accompanied by torrential rain. These fires often start in several places at once, which is stretching the long arm of coincidence a bit too far.

Apart from the very rare instances of volcanos causing wildfires, what other natural causes could there be?
Comparison of wildfire frequency in tinder-dry uninhabited areas, well away from civilisation, versus frequency in or near similar but populated areas should give a good idea of the scale of the problem.

There was an interesting paper on this for the United States a couple of years ago:

Balch et al (2017) Human-started wildfires expand the fire niche across
the United States, PNAS, doi: 10.1073/pnas.1617394114

They estimate that in the coterminous U.S. human-started events account "for 84% of all wildfires and 44% of total area burned".  There is a marked spatial variation, with lightning-started wildfires occurring mainly in the more sparsely populated western forests.  If you have access, the paper's worth a read, it has lots of interesting figures picking apart the details.

It's worth noting that there are a number of reasons for human-started wildfires, which are could be classed as accidental, deliberate or careless:

  Human-started wildfires were caused by a variety of sources, including the US Forest Service-designated categories of equipment use, smoking, campfire, railroad, arson, debris burning, children, fireworks, power line, structure, and miscellaneous fires.

They also note that their data contains this, perhaps not unsurprising, feature:

  There was also a notable mark of American culture on the distribution of wildfires, with the peak day of wildfires occurring on July 4th, concurrent with Independence Day fireworks displays (Fig. 2). Indeed, Americans start over twice as many wildfires on July 4th as any other summer day.


Why autumn follows the rainy season My location is India (this is to mention the context). The question I submit here is a common man's query (the level of this question and the expected answer).
Water is essential for the growth of plants and trees. Why does then autumn follow the rainy season? When the rainy season brings so much water, which is essential for the growth of plants, why doesn't spring follow the rainy season?

The precise reasons for leaf shedding after monsoon aren't well known and studied, but there are vague reasons like optimising use of light and warmth for max photosynthetic gain. So the tree has a heavy load of leaves to grow fast in monsoon, and it fast depletes the groundwater if it keeps the leaves in the dry season. read the conclusion here: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1466-8238.2006.00213.x
Trees need to store reserves to allow their survival during winter and for bud flush and leaf growth in the following spring.
Generally it takes 2 weeks or a month for a deciduous tree to prepare dormancy/sleep time, to gather all the nitrogen, glucose and nutritive elements from their leaves.
If the plant keeps on growing when it's leaves are adapted to massive rainfall, it may lose the green leaves rather than gather useful elements and prepare for dormancy.
i.e. from this image you can see the winter stored sugar being used to grow new leaves, for this tree the spring is in april:
There's some interesting facts about leaves here: https://en.wikipedia.org/wiki/Autumn_leaf_color#Function_of_autumn_colors


How can I downscale daily values of relative humidity? I have a dataset (The ISIMIP interpolation of CMIP5 output) that contains daily values of the following variables:

 air_temperature (C)
 air_temperature_max (C)
 air_temperature_mmin (C)
 relative_humidity (%)

There are other variables (wind, downwelling long/short wave radiation, precipitation) that I suspect would not be useful for a first order approximation)

What would be an appropriate way to downscale from daily to hourly values?

I have an algorithm to do this when daily $rh_{max}$ and $rh_{min}$ are given. This assumes a peak $rh$ at 10AM and uses cosine to cycle between max and min

$$rh_{scale} \leftarrow \dfrac{1}{2}(\cos(2 * \pi * (0:23 - 2) / 24) + 1)$$
$$RH \leftarrow rh_{min} + rh_{scale} * (rh_{max} - rh_{min})$$

Similarly, I get hourly temperature $t$ thus:

$$t = t_{min} + \dfrac{1}{2}(\sin(2*pi*(0:23 - 10) / 24) + 1) * (t_{max} - t_{min})$$

However, it is not clear how I can do this when mean RH is given. I know this is difficult, and there are likely many ways of bringing in other data sets, but I would like a simple first-order approximation that is better than assuming that RH is constant within each day.

Your approach to calculate an hourly temperature and relative humidity independently could be problematic, as these variables are dependent on one another.  I'd be interested to see a plot of one such day of $t$ and $rh$ and then to calculate the water vapor mixing ratio or dewpoint from your values and see how it varies in response and whether it is realistic looking.

If all you have in mean $rh$ and and a min/max temperature, one approach might be to derive a mean temperature and then from that a mean water vapor mixing ratio.  This mixing ratio can vary through evaporation, condensation, boundary layer mixing, etc, but for a rough approximation you could assume it is constant.  If you assume a constant mixing ratio and a temperature profile (e.g. your sinusoidal assumption) you could calculate the $rh$ profile for the day.  Note that you'll have to assure that your temperature curve does not cool below the dewpoint. You have the mean $rh$ as a crosscheck for this method and can use that to iteratively adjust your method for obtaining the water vapor mixing ratio.

Your diurnal temperature profile will vary based on latitude, time of year, proximity to large bodies of water, and weather.  If you discount the weather you can get by with your sinusoidal approximation with your minimum temperature at local sunrise and your maximum temperature in the mid to late afternoon.  The amplitude of the sine wave will be dependent on the your location (e.g. coastal locations will have small amplitude changes and inland desert locations will have large changes).  With a constant water vapor mixing ratio this will yield the highest RH at the temperature min at sunrise and the lowest RH in the mid afternoon.

If you can provide a $t_{max}$, $t_{min}$ and $\overline{rh}$ and a rough idea of where on earth your are looking at, I can run some numbers and provide more detail on this method.


Why is radiation and total precipitation not available in ERA Interim Reanalysis at step 0? ERA Interim reanalysis http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc surface level variables such as radiation and precipitation, but also many others, are only available at time 0:00 and 12:00, and not available at step 0? I need 6-hour data and from what I understand regarding the step option, I want step 0 as I need data valid for the same time. What is the meaning of step in ERA reanalysis data?

I will use this data in a forest modeling simulation that needs 6-hour data.

The ERA archive description document, Berrisford et al (2011) "The ERA-Interim archive Version 2.0", provides additional information about what is available.  It's less explicit on the why, but we can read between the lines a bit.

The archive consists of re-analyses of the system state at 00, 06, 12, and 18 UTC and re-forecasts out to 10 days initialised from those 00 and 12 UTC states.  Table 9 of that document lists the variables (including the ones that you're interested in) that are stored as accumulations since the start of the re-forecast.  They are stored every 3 hours for the first day of the forecast (steps 3, 6, 9, 12, 15, 18, 21, 24) less frequently thereafter (every 6 or 12 hours).

The variables are not stored for step 0 because their accumulations would be exactly zero.

Regarding using ERA Interim for model forcing, you might consider what Balsamo et al (2015) do for ERA Land forcing.  They use state variables from steps 3, 6, 9 and 12 and accumulations from steps 12, 15, 18 and 21 (see Fig 1 of that paper).  This inconsistency is because the fluxes (accumulations) are particularly prone to spin-up artefacts in the first few hours of the forecast.  The trade-off is that the states and the fluxes used in the forcing come from slightly different forecasts.


What is the average color of soil? Where I live the soil is red.

Is there a map or chart where you can see the average color of the dirt according to geographical location?  What would the color be if all of the dirt on Earth was added equally to a pallet?

I understand that composition of minerals determines dirt color but what makes dirt its color is not the question I am asking.

Kata Tjuta, Northern Territory, Australia

Sagada, Mountain Province, Philippines

https://eugeneexplorer.wordpress.com/2016/11/22/blue-soil-hills/

Gentry County, Missouri, United States

http://www.airphotona.com/image.asp?imageid=11944

This gif, prepared by the United States Department of Agriculture - Natural Resources Conservation Services (USDA-NRCS) soil scientists at the National Soil Survey Center, has soil colors based on the Munsell Color System for the United States at different depths:

The soil colors nearest the surface are darker due to more organic matter and are lighter at depth with varying colors by region.

Source: http://munsell.com/color-blog/soil-colors-national-parks-anniversary/

This link also has soil colors of select United States National Parks.  For example:


What are some near term effects of Global Warming? Many of the predictions of Global Warming models are dated in the range of ~100 years or more from the present. I'm wondering if any models or data provide predictions for the more immediate future, say $10$ - $20$ years from today.

Specifically, I'd like to hear about predictions that directly influence humans, such as weather, flooding, disease, etc.

The IPCC AR5 chapter 11 covers near-term climate change. I recommend reading the executive summary (it's only 6 pages). My summary of the summary is that near-term climate change is like long-term climate change, but scaled down and with less certainty. Surface air temperatures and upper-ocean temperatures are likely to increase, with an associated increase in atmospheric water vapor. Precipitation is likely to increase where it's already high and likely to decrease where it's already low. Summer Arctic sea ice extent is likely to decrease as well. But there is something there that I want to highlight.

The end of the executive summary talks about near-term air quality, and the beginning talks about predictability. Specifically, it mentions that emissions of chemicals that produce aerosols -- atmospheric particles that interact with solar radiation -- have a wide range of uncertainty, even in the near term. Unlike CO2, aerosols can induce a significant climate response (or at least a change in radiation) over the span of weeks and months. A change in energy use or technology, like India and China adopting sulfur control policies, can thus affect climate quickly and dramatically. This is a source of a lot of the uncertainty in near-term projections; over the long-term, CO2 dominates.


Can impact events cause widespread volcanic activity on the other side of the planet? The currently accepted theory for P-T mass extinction is environmental change triggered by the Siberian Traps volcanic activity.

A paper(1) suggests that the Siberian Traps were caused by a hotspot created after an impact event on what was back then the antipode of Siberia: the Wilkes Land crater.

  Thus, the impact may have triggered the “Great Dying” at the end of the Permian and contributed to the development of the hot spot that produced the Siberian Traps and now may underlie Iceland.

However, another more recent review paper(2) mostly discredits this theory:

  Finally the recent report of a 500-km-diameter impact structure of possible Permian–Triassic age in the Antarctic(1), is based entirely on satellite gravity measurements, provides no geological context, and completely ignores the absence of any predictable regional and global geological effects from such a large impact event, e.g., the absence of any thick ejecta layer at nearby Antarctic Permian–Triassic boundary sections.

Leaving aside the discussion of whether such a thing caused the formation of the Siberian Traps and thus the P-T mass extinction, in theory, can an impact on one side of the Earth cause volcanism on its antipode?

Also very important, why would this happen? What's the supposed mechanism that converts short term seismic activity to volcanic activity derived from long term hot spots?

Note that I'm not asking about in situ volcanic activity (such as the case of Sudbury). The impact also has to be reasonable in magnitude: I don't consider the moon-forming event that destroyed the young Earth as a reasonable impact in magnitude.

(1) von Frese, R. R. B., L. V. Potts, S. B. Wells, T. E. Leftwich, H. R. Kim, J. W. Kim, A. V. Golynsky, O. Hernandez, and L. R. Gaya-Piqué (2009), GRACE gravity evidence for an impact basin in Wilkes Land, Antarctica, Geochem. Geophys. Geosyst., 10, Q02014, doi:10.1029/2008GC002149.

(2) Bevan M. French, Christian Koeberl (2010), The convincing identification of terrestrial meteorite impact structures: What works, what doesn't, and why, Earth-Science Reviews, 98, Issues 1–2, Pages 123-170, doi:10.1016/j.earscirev.2009.10.009.

edit 18/10/2015

There was a paper published recently in Science that suggests that this is exactly what happened in the K-Pg extinction event. The Chicxulub increased the intensity of the Deccan volcanism, on the other side of the planet. Here are some links:

Volcano-asteroid combo may have done in the dinosaurs

Could dino-killing asteroid have pumped up giant volcanoes?

edit 31/12/2016

Not everyone agrees! For example:

Triggering of the largest Deccan eruptions by the Chicxulub impact: Comment

Note: this is a part answer, based on recent research and modelling

There has been considerable research recently in what is known as antipodal disruption, in particular, a group from Princeton University have produced a model that overcomes the main deficiencies of commonly used models that have the Earth as a 'featureless sphere' (1)(2).  Simulations using a symmetric spherical Earth produce a deceptively large peak at the antipode (2) - this is often cited as being some form of proof for the P-T example that you provided in the question and an antipodal relationship between the Deccan Traps and the Chicxulub crater (1).

However, the Princeton team's simulation (1), (2) show that there ought to be an antipodal effect, but when the elliptical shape and the heterogeneity of the surface is taken into account - where the waves end up and their displacement when they get there are quite different to the spherical models (1), to the order of 4 times less displacement and the antipode effects are not on a point source (2).

This results in a disagreement with the Deccan Traps-Chixculub relationship, as shown in the late Cretaceous model below, from (1):

This has implications for not only seismicity, but for volcanism and hot spot activity, due to the modelled impact seismic waves (across the surface and through the Earth) showing to be unfocused and scattered, this results in less severe ground displacement, tsunamis, and seismic and volcanic activity than previously theorized. Their models showed that the antipodal region had 'chimneys' of peak stress, strain and velocity.

Meschede et al. 2011 (2) conclude from their model that there would be greater seismicity in the region around the antipodal 'chimneys', this increase in seismicity can trigger volcanism, and even though the impact energy has been modelled to be insufficient (by several orders of magnitude) to induce melting to form an antipodal hotspot.

Some ongoing research by Hagstrum, 2005 (3) has suggested that oceanic impacts may result in hotspot/large igneous province antipodal pairs, this is due to, according to Hagstrum, oceanic crust having a greater seismic efficiency that continental crust. The mechanism is, according to Hagstrum,

  an
  inherently antipodal mechanism of hotspot formation
  is proposed in which one hotspot forms at an oceanic
  large-body impact site and a second hotspot and
  possible LIP are formed from seismic energy focused
  in the lithosphere and upper asthenosphere at the
  impact’s antipode.

However, it is not clear if the non-spherical heterogenous nature of the Earth's lithosphere was taken into account, given that, as stated, the impact energy is insufficient to cause melting, Ivanov and Melosh (4) state that the seismic mechanism may contribute as a trigger for a "pregnant" hotspot to activate, not through melting, but through increased seismicity (fracturing rocks etc).

(Note, the use of "pregnant" is their words, not mine)

Conclusion

The models created by Meschede et al. (2) have found that it is theoretically possible for localised antipodal volcanism to occur, but this volcanism would not necessarily be the direct result of the impact itself, but due to the contribution of an increase in antipodal seismicity (increased earthquakes fracturing rocks in the lithosphere etc).

Meschede et al. (2) contend that their model indicates that the impact energy is very much insufficient to result in a sustained mantle plumes and hotspot volcanic regimes as in the previous models.  However, there is still ongoing research about the impact energy contribution to the formation of hotspots and 'traps', particularly for oceanic impacts (3), but this is very much uncertain (2) and unlikely to be the direct cause (4).

References

(1) Kelly, 2011, Impact study: Princeton model shows fallout of a giant meteorite strike, News at Princeton, Princeton University

(2) Meschede et al. 2011, Antipodal focusing of seismic waves due to large meteorite impacts on Earth, Geophysical Journal International

(3) Hagstrum, 2005, Antipodal hotspots and bipolar catastrophes: Were oceanic
large-body impacts the cause?, Earth and Planetary Science Letters

(4) Ivanov and Melosh, 2003, Large Scale Impacts and Triggered Volcanism, in Large Meteorite Impacts


Are there any other earthquake magnitude scales other than Richter's? There are sometimes confusion about the magnitude of Earthquakes. What scales, other than Richter's, are used to measure the magnitude of an earthquake?

Is there a scale where magnitude 9.0 is regarded as small and 13-14 regarded as strong?

Earthquakes are measured for intensity and magnitude. Magnitude and intensity are related but measure very different properties of the event. Magnitude is the energy released of the earthquake. It is determined from measurements. Intensity is determined from effects on buildings, landscape and people. Naturally an earthquake with high magnitude would also generate high intensity, but the intensity depends on distance from the hypocenter and the local geological conditions.

Modified Mercalli Intensity scale is a way to rate the intensity of an earthquake, but the scale ends at XII (Damage total), not at 13-14 (XIII-XIV), as mentioned. China seismic intensity scale (CSIS), Medvedev–Sponheuer–Karnik scale and European macroseismic scale can reach values above ten, but not 13-14. XII on the Medvedev–Sponheuer–Karnik scale is Very catastrophic and IX in Destructive.
Medvedev–Sponheuer–Karnik scale is used in some Asian and European countries,  Russia, India, Israel etc. CSIS is used in mainland China.

Magnitude is also measured in different scales. Related to the Richter's scale is the Moment magnitude scale, it's an updated better way to measure, but it usually produce similar values as the old Richter's scale and the two scales are often confused in media. There are few other scales, Body wave magnitude, surface wave magnitude, but to my knowledge they also stay under 10.

Some of the confusion might come from that the Richter scale is logarithmic. A difference in magnitude of 2.0 is equivalent to a factor of 1000. An earthquake measured to 9.0 is one million times stronger than an earthquake at 5.0.


When GCMs are calibrated do they use 'corrected rainfall' input? Part of calibrating Global Climatic Models involves 'hindcasts' or 'history matching' against historic climate records, including rainfall. Such rainfall records are all in error because almost all raingauges incur at least a 7% aerodynamic under-catch. Conventionally this is not 'corrected' but for model calibration they should be corrected. So are GCM using corrected or uncorrected rainfall inputs? If yes, how are the rainfall records corrected - just multiplying by 1.07, or some other way? If no, why not? This is important because, worldwide, the GCM outputs are being used for forward projections of water resources (even though that is not what GCMs are designed to support).

Precipitation is the results of physical processes. As each model implement convective and thermodynamic processes differently (mainly through parametrization or imposed by different grid cell resolution), each model will produce different precipitation. Hence, in other words, you can't tune precipitation, but you can tune the parameters that will produce precipitation. As rainfall is not an easy observable, especially in the period usually used for tuning (~1850-1900), climate modelers does not use such information for their tuning.

Mauritsen et al. (2012) gives an interesting overview of this subject. The abstract is given below. From this article, it states (emphasis are mine) :

"[...] Formulating and prioritizing our goals is challenging. To us, a global mean temperature in close absolute agreement with observations is of highest priority because it sets the stage for temperature-dependent processes to act. For this, we target the 1850–1880 observed global mean temperature of about 13.7 \deg C [Brohan et al., 2006]. Beyond that, we prioritize having globally averaged TOA shortwave absorption and outgoing longwave radiation in good agreement with satellite observations, along with a representation of important climate variability modes. [...]"

Abstract

"During a development stage global climate models have their properties adjusted or tuned in various ways to best match the known state of the Earth’s climate system. These desired properties are observables, such as the radiation balance at the top of the atmosphere, the global mean temperature, sea ice, clouds and wind fields. The tuning is typically performed by adjusting uncertain, or even non-observable, parameters related to processes not explicitly represented at the model grid resolution. The practice of climate model tuning has seen an increasing level of attention because key model properties, such as climate sensitivity, have been shown to depend on frequently used tuning parameters. Here we provide insights into how climate model tuning is practically done in the case of closing the radiation balance and adjusting the global mean temperature for the Max Planck Institute Earth System Model (MPI-ESM). We demonstrate that considerable ambiguity exists in the choice of parameters,and present and compare three alternatively tuned, yet plausible configurations of the climate model. The impacts of parameter tuning on climate sensitivity was less than anticipated."

Citation

Mauritsen, Thorsten, Bjorn Stevens, Erich Roeckner, Traute Crueger, Monika Esch, Marco Giorgetta, Helmuth Haak, et al. 2012. “Tuning the Climate of a Global Model.” Journal of Advances in Modeling Earth Systems 4 (3): n/a – n/a. doi:10.1029/2012MS000154.


Are there probably decent oil fields located in the middle of the ocean? I did a google image search for a world map of offshore oil. Surprisingly I found virtually nothing. I had to search country by country for such maps.

I noticed most if not all were located very near the country's shore, on the continental shelf. These are fairly shallow seafloors, not even going below 1 km deep.

I guess this is because, it's easiest to explore (and drill) in the shallow regions first. But what I want to know, is there good reason to believe the very deep ocean also has oilfields.

So here is my question: Given our current understanding of geological history, is it likely that the oceans have decent oilfields located underneath the very deep seafloor?

"Decent oilfield" would be something like 10+ million barrels of oil without more sulfur than a Heavy Grade of Crude.

We have good bathymetric data of most oceanfloor, e.g., the underwater mountain-range in the mid-Atlantic, and the superdeep trenches following the Mariana Islands. I'm hoping that just by looking at the shape, we can make a good prediction where oil is located.

My only hint is a few very deep regions in the Gulf of Mexico, like this field that's 2.7 km below the sea. I am not aware of any other deep offshore platforms. I noticed the Gulf of Mexico has a fairly...what's the word here...bubbly shape in the deep parts.

Are there probably decent oil fields located in the middle of the ocean?

tl;dr: no.

Hydrocarbon deposits form by thermal maturation (i.e. slow and mild heating) of buried organic matter (i.e. dead things) in sedimentary rocks. This is exactly why you find hydrocarbons...

  very near the country's shore, on the continental shelf

...because that's exactly where you find sedimentary rocks.

In contrast, the deep ocean basins are igneous rocks (mostly basalts) overlain by thin marine sediments with very little organic material. Whatever organic material is there, it never has the chance for maturation. It's either very cold, or gets heated in subduction and is lost forever in the deep mantle.


Impact craters under water What would be the resulting impact crater of a meteorite hitting bodies of water on Earth?

Let's take for example the impactor that resulted in Meteor Crater, Arizona. What would the impact look like if it hit a shallow sea? A deep ocean? Is there any depth of water which would result in no crater at all?

You don't need much of a depth to be able to stop a meteorite. Less than 100 m water depth should be enough to stop such a meteorite as shown in the provided link without any particular crater on the sea bed.

The Physics part of the story is provided here;

The rest is mathematics.

Short. At collision all the kinetic energy is transferred to Pressure, and thereafter this pressure is again transferred to kinetic energy; it is explosion. Very simply said it's Bernoulli principle.

By this reason it doesn't penetrate practically any deeper in water than in Earth, and as the water then smooths up you have no crater. A very simple scaling might be made with density; typical rock / water; 2.3/1 depth.

If you need some visual proof, try this video;

https://www.youtube.com/watch?v=cp5gdUHFGIQ


How stormy (wave height) does Lake Baikal get? I'm trying to find info on the storminess of Lake Baikal. I want to compare wave heights in a storm on this lake to wave heights in a storm on the ocean.

All I could find was very general information that Lake Baikal experiences a stormy season in autumn with approximately 18 stormy days per month. I could not find any hard statistical data on waves or winds.

An article here says 4 meters. (No statistical data however, just a general information page)

  Waves on Lake Baikal may reach a height of 4 meters. Sometimes they
  evaluated as 5 and even 6 meters, but it is most likely an estimation
  “by eye”, which has a large error. Height of 4 meters obtained by
  instrumental measurements on the high seas.

Another source, The Lakes Handbook: Lake Restoration and Rehabilitation
edited by Patrick O'Sullivan, C. S. Reynolds, (pg 179) agrees with this figure (emphasis mine):

  Baikal exhibits many features of an ocean: abyssal depth, internal
  waves and seiches, tides, violent storms in which wave-height
  reaches up to 4m, and deep water luminescence of uncertain nature.


How to tell the difference between real rain and fake rain (cloud seeding)? I live in a city where the pollution is bad, so bad that sometimes we get 'fake' rain (from cloud seeding). This may last for an extended period.

There have been times before when it has “rained” and it might as well have been raining.

This seems to defy some sort of logic though. Natural rain and human produced rain must have some fundamental differences, should they not?

What differences exist between natural rain and human “rain”?

What differences exist between natural rain and human “rain”?

The only physically measurable difference between rain from seeded clouds and unseeded is in the seeds/ cloud condensation nuclei/ aerosols that are the surface that moisture can condensate onto and form cloud droplets.
Measurements
You could collect rainwater, evaporate it and the remaining solids were the substances acting as cloud condensation nuclei. This process would get some aerosols from the ambient air, but simultaneously using a device for collecting aerosols and reducing their composition from the rainwater one would lessen this problem. After analyzing the solids one could do some guesswork whether the aerosols were natural or influenced by humans. For example if there is actually deliberate cloud seeding happening you could find traces of silver iodide. Most likely this is not the case and simply heavy pollution has a significant impact on formation of aerosols that can act as cloud condensation nuclei. In this case there are probably some compounds that can be formed only in combustion processes and finding them would mean that they played a role on the formation of the clouds. Doing this experiment in otherwise similar locations with the other having much more pollution would probably be the sanest option. Even after all this you still wouldn't be able to accurately tell whether it would've rained more or less without the pollution. If the air is clean to begin with, adding pollution and thus aerosols the cloud formation would be enhanced and probably then rain too. But if the air already has enough cloud condensation nuclei to begin with then adding aerosols might have the opposite effect; moisture would condense into many small droplets rather a few big ones that create rain.
Modelling
Another possibility would be to study this using a weather model with aerosol dynamics included using measurements of the given location to verify the results. And when the model simulates the reality accurately enough you could tamper with the aerosol fields (by adding and reducing aerosols) and see how the rain is affected. I'm not aware how accurate these kind of models are currently, but aerosol dynamics can make the model easily very heavy.


Does crustal thickness have anything to do with how life existed and sustained on Earth? The original question that was put on hold "If the crust were the thickest layer of Earth, what effect would its thickness have on organisms?"  was actually one of those 'counterfactual question' found on my science book, and it was really just a 'reflect upon' question. And it's actually a hard one for me to answer since it's 'what if?'s. So by revising, it would still confuse some poeple, but I guess it's already specific on its own. But I still find it hard.

Follow up question:

And what if it ever was thicker than the mantle or the rest of Earth's layers, can the planet still sustain biological life?

If the crust were the thickest layer or Earth, several things would happen:

It wouldn't be a "crust" any more, by definition. Because this is what a "crust" is: a thin layer on the exterior of something. However, if we assume that the mechanical properties of the crust (being cold and brittle etc) would extend deeper in the Earth, the following applies.
No mantle convection, or at least mantle convection weak enough to probably not affect the surface. Therefore, no volcanoes, no mountain building, no subduction, no recycling of volatile elements, no sub-seafloor hydrothermal vents.
If it's cold enough, the core probably solidified and there is no magnetic field.

A good example would be Mars. A planet hypothesised to have tectonic activity in the past, but not any more. The crust of Mars isn't the thickest layer (again - think of definitions), but it is thicker in absolute and relative terms when compared to Earth. I will leave the implications of "Marsifying" Earth on organisms for you to figure out.


Erosion without weathering? In one of my Geography books, the following sentence is written:

Though weathering aids erosion, it is not a pre-condition for erosion to take place.

How can I justify this? Almost all the forms of erosion that I know happens on weathered rocks. Do we have any examples of erosion without weathering? As weathering means to strip off or to uncover, and erosion means to transfer.

So far I came up with one example: Blast eruption of volcano makes small stones and pebbles, which could be carried by waves, rivers etc.

Your concept of weathering is erroneous. It is not uncovering or stripping off material. Weathering is a very slow process of breaking down rocks, soil & minerals, in-situ, via contact with the Earth's atmosphere, water & biological organisms. This can also involve heat & pressure.

Erosion, as you state, involves the moving of material. This can happen due to the action of running water, the impact of water via waves on coastal environments, wind or glaciers dislodging grains of geological material irrespective of whether it is weathered or not. Landslides are another form of erosion.


What CRS does GFS use? I'm trying to reproject GRIB data from NOAA forecasts onto other data using Python and the pygrib and proj packages (among many others). What is the proper Proj string for GFS GRIBs?

The projection should come from the GRIB file and I assumed GFS uses Mercator, but pygrib grib.projparams() returns
{'a': 6371229, 'b': 6371229, 'proj': 'cyl'}. 'cyl' is not a legal proj CRS and other cylindrical projections (Central Cylindrical, Plate Carree) don't have a or b parameters. I assume that a & b are defining the earth as a sphere with radius 6371229m.

grib.projparams() with an HRRR GRIB returns
{'a': 6371229, 'b': 6371229, 'proj': 'lcc', 'lon_0': 262.5, 'lat_0': 38.5, 'lat_1': 38.5, 'lat_2': 38.5}

which is perfectly legal in the eyes of Proj and reprojects data accurately.

My ansatz for what cyl means is likely Equidistant Cylindrical Projection, because in the older Basemap module, 'cyl' was the shortname for that projection.
But the reality is that since the GFS is a global spectral model with a latitude-longitude grid, it likely does not require a CRS. That is, it presupposes a sphere, where a CRS projects the spherical coordinates (latitude, longitude) onto a shape (such as a cone).


Will kerosene reserves deplete long before oil? Assuming that the oil reserves would end at a certain date, would it be expected that the kerosene be no longer used as fuel on a previous date due to the quality fall of barrels?

If so, would that date be much more previous in absolute or relative terms?

No.

At the moment, we use cracking to turn heavy, long-chain hydrocarbons into more valuable short-chain hydrocarbons, such as petrol/gasoline and kerosene; as a general rule, lighter hydrocarbons are more valuable, at least up to butane.

Generally, it might take the form:

C$_{16}$H$_{34}$ $\ce{->}$ 2 C$_8$H$_{18}$  (Octane, a typical petrol component)

Note that this is not balanced; to crack to fully-saturated products we need to add hydrogen, usually made from natural gas and water. This is why you sometimes see that a refinery will take 1 tonne of heavy crude and make 1.1 tonnes of petroleum products. This is called 'refinery gain'.

Essentially, as long as we have hydrocarbon feedstocks, we can make kerosene.


Is the gulf stream both a wind-driven current and part of thermohaline circulation? Currents are formed in 3 major ways:

Tidal Currents
Wind-driven Currents
Thermohaline circulation

I've seen the gulf stream mentioned as both a wind-driven surface current and being part of the thermohaline circulation, which is due to density differences.

Does the gulf stream belong to both classifications of currents?

Yes.Thermohaline circulation is dependent on differences in water density, caused by differences in temperature and salinity between different bodies of water. It therefore requires deepwater areas, of which the northern and middle Atlantic have the most, for these differences or "gradients" to form. These are influences on the Gulf Stream.

In addition, the Gulf Stream is wind driven, as is true of most currents. So it depends on both influences.


Is astrochronology a proper method? Wikipedia's definition of astrochronology is:

  "Astrochronology is the dating of sedimentary units by calibration
  with astronomically tuned timescales, such as Milankovic cycles,1[2]
  or even sunspot cycles. When used in concert with radiometric dating,
  it allows the resolution of timescales to a high degree of accuracy.
  If orbital precession cycles are identified, the dating error can be
  as low as 21,000 years."

  source: wikipedia

Question:

  Is this method really used and does it have a good reputation among field geologists?

Yes it is used and it works. I've heard varying viewpoints on it's accuracy and dependability though. I remember my earth science lecturers were in three camps with it:

one felt that the dates weren't consistently reliable, the data he'd gotten from astro-dating in the past had very poor independent confidence margins when there was no radiometric calibration. He implied that the results felt as though they had been pulled out of thin air.
two would gather testable material for future study but didn't use astro-dating themselves. It was an interesting but immature technique that might be useful in future but not to them.
only one felt that it was really, immediately useful.

Do note that this is in New Zealand, we're a geologically young and active country, so much so that we rarely need longer range radiometric testing like Uranium-Lead or even Potassium-Argon, we can Carbon date most of the sites we're interested in. Fine calibration of longer range datings is much less of an issue here than in older, more settled, locations.


What are the possible mechanisms that could cause a rapid drop of temperature over few days? I live in Hong Kong. Two days ago, the average daily temperature was around 27–28 °C and in yesterday, it was around 22–23 °C (during daytime it was rather hot i.e. 26–27 °C and it was at night that the temperature plummet) and today it is 19–20 °C in the morning. I am a newbie in climate/weather science so I would be very much appreciated if you can provide a more comprehensive answer.

If you look at the first picture, it is the barometric (atmospheric pressure) map of the Honk Kong region for 12 October 2015, from the Hong Kong observatory website. Barometric maps don't change radically over the a period of a few days. The second picture is a similar map for the south east Asia region as at 8 am on 11 October 2015. It is from the same web page as the first picture, I just selected an earlier date from the upper right of the page.

Some things to note about the first picture:

Temperatures in Beijing, Seoul and Hong Kong are 12, 10 and 21
degrees Celsius respectively. It's much colder in Beijing and Seoul than it is in Hong Kong.
There is a high pressure system to the north of Hong Kong and to the
west of Shanghai which appears is part of a larger high pressure system WNW of Beijing. There also appears to be a low pressure system to the
north of Japan (which is confirmed in the second picture).

In the northern hemisphere, air flows clockwise around high pressure systems and counter-clockwise around low pressure systems.

The affect of the high pressure systems over China combined with the low pressure system to the north of Japan is to funnel cold air from the northern latitudes to the southern latitudes. This brought a significant amount of cold air to Hong Kong which caused the temperature to drop.

If you look at Manila, in the Philippines, it is a relatively short distance from Hong Kong. It's temperature is 27 degrees Celsius compared to 21 for Hong Kong.

If you look at the first picture, there is a low pressure system just to the west of the Philippines. With air moving counter-clockwise around low pressure systems, warm air from the equatorial regions is being drawn northwards along the western parts of the Philippines maintaining a very warm temperature in Manila.

Currently, Hong Kong and Manila are being influenced by different weather system and that's why there is a significant difference in the temperatures between the two locations despite their close proximity.

Barometric Map of Hong Kong for 12 October 2015

Barometric Map of South East Asia as at 0800 11 October 2015