Why does aragonite form in one case and an acetate in another? If I add acetic acid to limestone, I can get calcium acetate crystals to grow but if I add acetic acid to dolomite, supposedly I can grow aragonite which is a form of calcium carbonate.

Why would I get crystals of an acetate in one instance and a carbonate in the other? And, what happens to the acetate ion and the magnesium when forming aragonite?

I know that aragonite can form instead of calcite because of something called "magnesium poisoning" but I still do not understand how any carbonate is formed when dolomite is immersed in acetic acid.

Common Ca carbonates on Earth's crust have different concentrations of Mg. There is High Magnesium Calcite and Low Magnesium Calcite.
Aragonite has in comparison to calcite high levels of Mg.

If you mixed trusted dolomite with an acid and you took aragonite, a carbonate similar to dolomite but with lower levels of Mg, I suposse aragonite is an intermediate carbonate product in the reaction instead of the complet decomposition of the dolomite. Dolomite is decomposed with HCl at high temperatures and not as quick as calcite. So the high concentration of Mg of the dolomite should alter the thermodynamical equilibrium.

The sequence of the reaction is:

Destruction of dolomite crystals.
Formation of aragonite. --> excess of Mg.

The Mg liberated from dolomite structure follows two ways. Aragonite accepts a low concentration of it. Then surplus Mg could be considered chemical waste while acetic acid is a chemical reactant.
In the case you get calcium acetate, acetic acid accepts Ca and it is transformed, but in this case is just a chemical reactant and his structure is not modified. Note the main difference is there is not excess of Ca.


Why is satellite imagery data delivered as signed 16 bit integers? Landsat 5 tm  reflectance product images are delivered as signed 16 bit images, why is this preferred to unsigned 8 bit that the DN's are stored as level 1 products for the same satellite? Look at table 6-1 on page 19 of the following document: https://landsat.usgs.gov/sites/default/files/documents/ledaps_product_guide.pdf.

Because the surface or top-of-the-atmosphere products are not raw data. Atmospheric corrections have been applied to the raw data and those corrections have been done with a precision that can't be properly captured in 8-bit numbers. You can round data outputs to 8-bits, but there would be information loss.
Some bands, like atmospheric opacity can be calculated by the model with high precision, and you need a 16-bit number to store such precise values.
Although the values are stored as 16-bit integers they are floating point numbers, and the scale factor is provided in the same table you mention.

I also think that it have to do with having a coherent data format across all the Landsat derived products, including Landsat 8 that have the OLI sensor with a spectral resolution (or bit depth) of 12-bit, that means that the intensity of each pixel is recorded with a number between 0 and 4095, something that provides much more information than the traditional 8-bit (Used by Landsat 7 and before), were intensity is recorded with values between 0 and 255.
Additional bits give more information and is specially useful to distinguish details in areas with low contrast, like shadows, water or snow fields. For example, all the shades of white in a snow field that corresponded to just one color in Landsat 7, can correspond to 16 different colors in Landsat 8.

Data is distributed in 16-bit files because computers are optimized to deal with 8, 16 or 32 bit numbers, and most software reads images with those bit depths. Therefore, a 12-bit file would not be very compatible, and the smaller standard file that can store all the information of a 12-bit image is a 16-bit data file.

The bands that use 8-bits in the table 6-1 that you mention are quality control bands, that contain information that can be stored in 8 bits without any loss in performance.


Is "Chasm One" the really the name of this feature on the Brunt Ice Shelf? The BBC News article Antarctic: No role for climate in Halley iceberg splitting says:

  With no-one on the ice surface, notice of any breakaway will have to come from automated in-situ instrumentation and from spacecraft observations.

The image below shows the current location of Halley Research Station relative to "Chasm One". I like that name. It reminds me of SpaceShipOne and Public Enemy No. 1.

Is "Chasm One" an "official" name for the feature? How was the term coined? Will there be a new Chasm One someday, or will the name be retired after this one splits?

Source: NASA, LandSat, USGS, BBC

Is "Chasm One" an "official" name for the feature?
No. This is only an informal name used to designate a rift structure (fracture) in the Brunt Ice Shelf, East Antarctica. For example, another rift structure, which trends perpendicular to "Chasm 1," was informally named the "Halloween Crack" because it was first detected on October 31, 2016.

How was the term coined?
It is one of two rift structures that are arbitrarily and sequentially numbered, "Chasm 1" and "Chasm 2", starting from the seaward edge of the Brunt Ice Shelf, East Antarctica inland along the ice shelf as shown in Figures 1 and 2 0f King et a. (2017).

Will there be a new Chasm One someday, or will the name be retired after this one splits?
The name will likely be retired because having multiple "Chasm 1"s in the same ice shelf will be too confusing. Most likely as new rift structures from the sequential naming of them, e.g. "Chasm 3," "Chasm 4," and so forth would continue.

The papers are:
de Rydt, Jan, Gudmundsson, Hilmar, Nagler, Thomas, Wuite, Jan and King, Edward (2018) Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica. The Cryosphere, 12 (2). pp. 505-520. ISSN 1994-0424 http://dx.doi.org/10.5194/tc-12-505-2018
de Rydt, J., Gudmundsson, G. H., Nagler, T., and Wuite, J.: Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice-shelf geometry, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-46, in review, 2019 https://www.the-cryosphere-discuss.net/tc-2019-46/
King, E. C., De Rydt, J., and Gudmundsson, G. H.: The internal structure of the Brunt Ice Shelf from ice-penetrating radar analysis and implications for ice shelf fracture, The Cryosphere, 12, 3361-3372, https://doi.org/10.5194/tc-12-3361-2018, 2018. https://www.the-cryosphere.net/12/3361/2018/
Hodgson, Dominic A., Jordan, Tom A., de Rydt, Jan, Fretwell, Peter T., Seddon, Samuel A., Becker, David, Hogan, Kelly A., Smith, Andrew M. and Vaughan, David G. (2019) Past and future dynamics of the Brunt Ice Shelf from seabed bathymetry and ice shelf geometry. The Cryosphere, 13. pp. 545-556. ISSN 1994-0440 http://dx.doi.org/10.5194/tc-2018-206


Could diamonds be formed from coal? Diamonds are predominately formed in cratons and brought to the surface in kimberlite pipes.  However, it seems theoretically possible that diamonds could form at either subduction zones or from meteorite impact sites where the temperature and pressure would be suitable for diamond formation in the presence of coal. - source.

Is there any evidence of diamonds being formed from coal at a subduction zone, or from a meteorite impact, and if so, where did this occur?

Craters actually can be identified by formation of high-pressure materials such as diamonds or stishovites and coesites (varieties of shocked quartz). A good example of this is the Popigai crater in Russia.

Pressures and temperatures at subduction zones are usually too low to form big diamonds but microdiamonds (10-80 microns) were discovered within metamorphic rocks related to continental collisions. There are five well confirmed diamond-bearing terranes, the Kokchetav massif of Kazakhstan, Dabie and Quinlin in China, the Western Gneiss Region of Norway, the Erzgebirge massif of Germany, and the Kimi complex of the Greek Rhodope (according to the paper http://www.pnas.org/content/104/22/9128.long).


The differences in gases produced by asteroids impacting crystalline and sedimentary rocks A second question inspired from How Long Will Life Last On Earth, The Manicouagan crater in Canada is one of the largest impact crater on Earth.  It was created 215 million years ago, but its formation did not trigger a mass extinction event. It is claimed that this is because the impact occurred in crystalline rock. It is also claimed that had the event occurred in sedimentary rock clouds of climate-changing gases could have been released into the atmosphere, which could have triggered a mass extinction.

What different gases could be produced by a significant asteroid impact in crystalline and sedimentary rocks?

A New Scientist article (with a somewhat amusing title) Fracking Hell investigates this exact question in some detail.  The difference is made by an analogue to the process of fracking.

Instead of the water use in human-engineered process of fracking breaking the underlying rocks up to release the methane for commercial purposes. The considerably larger impact of an asteroid does the same thing in a massively uncontrolled manner - in sedimentary rocks, it pulverises the sedimentary rock, releasing the gases that were trapped in it, such as sulphur from evaporites in the vicinity of the Chixculub impact; other gases can include hydrocarbons, halocarbons (salt + hydrocarbons), chlorine to name a few.

The amount of gases released from within the sedimentary rocks were enough to cause mass extinctions (in an essentially extraterrestrial version of what is believed to have occurred during the Siberian Traps event).

In crystalline rocks (such as igneous and metamorphic rocks), according to the article, the rocks are far more stable and do not release such amounts of climate changing gases than sedimentary strata in an impact event.  Although these rocks can contain gas bubbles etc, they have been found to relatively 'inert; in terms of gaseous release compared to sedimentary rocks, such as the 100km diameter Manicouagan crater in Canada, an event not associated with a mass extinction.

Essentially, the impacts can be devastating for either scenario, but the impact itself is not the only cause of mass extinctions, it appears that a large factor of the mass extinctions is due to the climatic change that results from the released gases uncontrollably 'fracked' out of the sedimentary rocks. Of course, if an impact is large enough, it could pulverise several layer of rock unlocking deep pockets of gases.


Why doesn't Earth absorb our carbon emissions? If we look at the carbon cycle, we see that man-made carbon emission only account for a tiny fraction of all $\text{CO}_2$ emissions.

However, we see a steady rise in atmospheric $\text{CO}_2$-levels.

Wouldn't it be logical to assume that earth would somehow adapt to this increase, e.g. through increased plant growth and why isn't this happening?

That assumption is indeed logical and correct, and increased plant growth is in fact happening (this effect is known as $\ce{CO2}$ fertilization). As you suggests, Earth will adapt to the increased inflow of $\ce{CO2}$, and it will find equilibrium again. What might be missing in your reasoning, is the fact that the atmospheric $\ce{CO2}$ concentration in the new steady state would not be the same as the concentration in the pre-industrial steady state.

The atmosphere is a reservoir of $\ce{CO2}$. Its has sources (volcanoes, plant respiration, decomposition, fossil fuels combustion, etc.) and sinks (photosintesys, ocean uptake, silicate weathering, etc.). To simplify the system let's do an analogy with a bath tub.

Let's imagine a bath tub with a very powerful faucet and a sink.
Now let's start opening the faucet until the sink becomes overwhelmed by the incoming water and the level in the bath tube starts to rise.
As the level rise, the water pressure at the bottom will rise too, therefore, more water will rush through the sink. Eventually the water going trough the sink will match the water coming in, and the water level will stabilize. At this point we have reached steady state.

If we open the faucet a bit more, the water level will rise again, up to a point where the bottom pressure allows the sink to catch up and a new steady state is reached, but this time at a higher water level. Also, note that after we increase the inflow of water, it takes some time to reach the new steady state, and that time depends on the sizes of sources and sinks relative to the reservoir. In our example, if the same faucet and sink were in an Olympic swimming pool instead of a bath tub, the time would have been much larger.

Going back to Earth, the atmospheric $\ce{CO2}$ concentration was pretty much as steady state before the industrial revolution (if we consider ~1000 years time scales). Then, with the industrial revolution we increased the inflow of $\ce{CO2}$ into the atmospheric reservoir. As a consequence, the ocean and erosion increased their $\ce{CO2}$ intake, and plats increased their photosynthesis rate. In that way Earth, as you correctly assumed is working its way back to a new equilibrium. However, to reach that equilibrium takes time, and once we reach it, the atmospheric $\ce{CO2}$ will be higher than the pre-industrial levels, and that will in turn lead to a stronger greenhouse effect, higher temperatures, and climate change.

It is also important to note, that the extra inflow of $\ce{CO2}$ didn't just increase at one point and stopped (like our faucet). It is constantly increasing to higher and higher levels of $\ce{CO2}$ production, making even harder for natural systems to bring Earth to a new equilibrium.

The first figure in the Wikipedia article you linked shows this neatly:

We can see here in white numbers the most significant pre-industrial sources and sinks (at ~1000 years time scales). We can see that humans produce 9 Gigatons of carbon per year (GtC/yr), due to that extra inflow, photosynthesis is taking 3 GtC/yr more than before, and the ocean is taking an extra 2 GtC/yr as well. However, that is not enough to counteract the 9 GtC/yr we produce, and that is increasing the amount of carbon in the atmosphere at 4 GtC/yr. This means the level in the atmospheric "bath tub" is still rising.

If we were to keep those 9 GtC/yr we produce stable (i.e. not increasing production in the future). The concentration of $\ce{CO2}$ in the atmosphere will rise to a level high enough that the sinks will match the sources, for example with plants taking 5 GtC/yr and the ocean 4 GtC/yr, that would nicely balance the production. But that new equilibrium atmospheric $\ce{CO2}$ concentration would be high enough to rise Earth's temperature several degrees and force a whole reorganization of the Earth's climates.

Finally, we have to say that some of these $\ce{CO2}$ intakes, like the oceanic one, don't come for free, and have their own nasty consequences, like ocean acidification.


Status of overdue glaciation hypothesis What is the status of the Early Anthropocene hypothesis, in the specific meaning that the climate would be projected to be significantly cooler (such as, on the order of by 0.8 degrees in the planet average) in a year corresponding to, say, 1800, if there was no agricultural revolution and no significant impact of our species on the climate starting several thousand years before that?

This is a layman's question.  I'm familiar with Ruddiman's work and some of its early criticisms, but I'm unsure what the current generation of scientists thinks about the issue and if there's any strong recent evidence either way which I should read about.

Please don't focus too much on my use of the terms "anthropocene" or "glaciation" themselves in this question, but feel free to suggest better ways to refer to the above hypothesis or its current successors.

Our interglacial ends some 1500-years from now, the AGU recently recognized the Holocene as geo-engineered by people converting forest to agriculture.

We passed a warm-ocean tipping point for northern hemispheric winters, frozen oranges in Florida and rain in Alaska now will be common.

Our emissions rate is far beyond natural systems, the rate of change coming out of the last ice-age was 1-ppm/180-years, we hit 3ppm/year in 2016, 540-times faster.

And, the max CO2 during the late Pleistocene was 305-ppm, we hit that in 1916 and added 100-ppm in 100-years.

This carbon bomb is acidifying the oceans 10-times faster than the worst land extinction in geologic history.

It's very unwise what we're doing.


Why does Earth's outer-core rotate in the opposite direction to the inner-core? Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core?  Is there a plausible explanation for why this phenomenon occurs and what is the available evidence supporting this notion?

Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core?

No. You misread a badly written for-the-masses science article. The article summary is at best rather confusing and misleading. It invites a reader to misinterpret what's going on.

So what's really going on? It's simple, conceptually. The mantle, outer core, and inner core all rotate in more or less the same direction and at more or less the same rate. However, because outer core is liquid, there exists a possibility for the mantle, outer core, and inner core to exhibit slightly different rotation rates (and perhaps even rotation axes). That's apparently what is happening inside the Earth. The mantle and crust make one rotation per sidereal day. The inner core currently rotates a tiny, tiny bit faster than that, while the outer core rotates a tiny, tiny bit slower than that.

This means that when viewed from the perspective of an Earth-fixed observer, the outer core currently appears to be rotating a tiny, tiny bit westward and the inner core currently appears to be rotating a tiny, tiny bit eastward. It's a matter of perhaps confusing perspective. When viewed from an inertial perspective, the mantle, outer core, and inner core are all rotating more or less synchronously.

When you read one of those science-for-the-masses type articles, it's a good idea to jump to the underlying journal article. In this case, you should try reading Livermore, Hollerbach, and Jackson, "Electromagnetically driven westward drift and inner-core superrotation in Earth’s core", PNAS 110:40 (2013).


Where can I find the record for the heaviest single-day rainfall ever recorded on any date at a specific location? I need to find out the largest amount of rainfall ever recorded in Atlanta, Georgia, USA. Where could I find this record?

Sounds like your question, like most questions about historical data, might be a little challenging to find the right source, as it often is around the world.

But seeing you said Atlanta brightened my eyes!

For if one is seeking information for a US climate observation sites (most big cities, and a fairly reasonable web across the US... there's about 2-6 per Weather Service office), then there's a great source for historical data that, with a little looking around, allows you to fairly quickly answer quite a lot of interesting questions about your area once you get used to doing it... the NowData portal on your local National Weather Service Office's website.  To find this:

Go to the National Weather Service.
Click on your local area (which will take you to your local NWS Office webpage)
Scan across the middle of the page about halfway up to find the climate and past weather drop down and you should come across the NowData link (for this one I had to click more in the menu)

Disappointingly tough to navigate to the NowData hub, but you only really need to find it approximately once, and then you're set!

To speed you along: this is the direct link for the Atlanta (Peachtree City) area.

Then, once you get to the NowData page, you want:

The Atlanta area as the selected location (that will combine the past and current official Atlanta observation sites together to go back as far as possible for the official Atlanta observation)
For product, click the calendar day summaries radio button
The year range should likely be good... you want por- (por = period of record, meaning back to the very start of record keeping)
Variable = Precipitation
Summary = Daily Maximum

And viola, click Go, and you'll have it.  No, it's not a single list.  In some ways, to some, it may be better, it's a page of the maximum precipitation values every day of the year.  (Which allows you to see other things that might pique interest... such that [as is common in precipitation data due to such wild variability], the days calendar days on which Atlanta has never received an inch of rain are: February 29, April 21, May 10, May 12, September 9, September 12?

Anyways, it's a bunch of numbers... but the extra positive is that the maximums for each month are highlight red.  So just search through those quickly, you should find that the maximum 24-hour recorded rainfall in Atlanta history is:

1. 7.36" on March 29, 1886

Second (assuming there was no additional great storm on a different March 29th!) was much more recent:

2. 6.68" on October 4, 1995

You may well be able to dig around the climate category on that Peachtree City National Weather Service page and find more information on the major storms including those, and a better, simpler list.  But if not, at least the NowData offers the chance to reliably get answers to many questions like yours.

I know, it's definitely not all the most intuitive.  At least it's consistent.  And, especially if you have some rudimentary spreadsheet experience, it can be made to tell you what you need rather quickly (in 15 years of meteorology, I still regularly use it myself.)  If somebody has a very reliable, comprehensive source for historical data that is fairly straightforward to the typical user, I'd be absolutely right at the front of the line to congratulate them.

(And it is indeed a real pity, that in an era where the big concern is supposed to be changing climate, it still is fairly abstruse and convoluted to get great comprehensive climate information in an intuitive way from an official source)

But hopefully, while it's not absolutely beautiful in method, it not only answered your question, but given you and others the tool to answer the same question and quite a few others on temperature\precipitation climate\history for many other cities around the country!


Pressure of condensation of an air parcel If a parcel of air ascends adiabatically, would condensation be reached at the lifting condensation level (LCL) or the level of free condensation (LFC)?

The lifting condensation level (LCL) is the level at which a rising particle reaches 100 % relative humidity by adiabatic cooling.

Please have a look at Wikipedia: LCL and LFC (level of free convection!).


Clouds moving in opposite directions Today driving to work I saw a small, isolated horse's mane cloud at about 2000 feet. Directly above it was a small strato-cumulous cloud at 4000 feet and and they were moving in opposite directions. The horse's mane was moving north and the strato-cumulous was moving south.

How could this happen? I imagine there must have been two layers of air, each moving in a different direction. In fact there must have been three layers of air, because the strato-cumulous would have been sitting on one layer and moving with the layer above.

This indicates that there was wind shear. Wind can change direction and speed with height.

Since air is a fluid, it's wind vectors can change with height. On a large scale, this is called the thermal wind balance. In the ocean, it is Ekman balance. On smaller scales, there isn't really a term that I know of that describes the balance, because it is rather turbulent.

As far as "How could this happen": What you saw was the mean flow over the height of one cloud, followed by the mean flow over the depth of another cloud.


How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's climate? I was thinking about this question, which may turn out to be simple, about climate dynamics: How does the amount of mass in an atmosphere affect the seasonal changes and dynamics of the planet's climate?  For example, while I know there are seasons on Mars, there surely isn't as stark of shift between seasons like Earth for example. Perhaps the amount of mass in the atmosphere really isn't a controlling variable? Perhaps composition or even distance to external heat sources is more important?

Seasons are determined by the degree of tilt of the planet's axis, not the mass of the atmosphere.  Mars has an axial tilt slightly larger than Earth, so Mars' seasons are slightly more pronounced than Earth's.  For a planet like Venus, which has virtually no rotation and an extreme axial tilt, "seasons" are also affected by the rotation/revolution ratio.

If you are interested in the climate differences between separate planets, mass of the atmosphere does affect overall global temperature (e.g. more atmospheric mass = more heat trapping) but the mass itself is not the main driver of the dynamic changes of climate within an individual atmosphere.  Really Mars and Venus don't have as much "short term" climate dynamics like Earth, because they don't have ocean/land dynamics.  Though, they definitely have seasons. Earth's "short term" climate dynamics are driven by the heterogeneous distribution of land, ocean, and (to a smaller extent) clouds.

All the planets do share similar long term drivers of climate dynamics, which on Earth are collectively known as the Malenkovitch cycles.  The Malenkovich cycles are on the order of 10s of thousands of years and include changes in axial tilt, axial precession, and orbital eccentricity.  Some would also argue that long term gravitational changes in orbit parameters due to trojan asteroids and large planets like Jupiter also affect the Malenkovitch cycles.  These cycles shift the timing, intensity, and spatial distribution of solar input to the planet.


Why don't forest fires in Western Australia get as much attention as forest fires in the southeast of the country (including SA)? WA gets plenty hot and dry in the summer (especially Exmouth and points south where Top End moisture isn't as prevalent), but I don't hear so much about catastrophic forest fires hitting WA, like I do about those that hit SA, VIC/TAS, NSW/ACT/SE QLD year in and year (it's events in these states that most often make international news), with the odd exception like the Perth bushfires of November 2011. Is there a meteorological or geological reason that the WA wildfire season can be forgotten as compared to wildfires in the eastern states of Australia?

Forest fires, and natural disasters in general, get attention when they affect people.

Bush fires outside of metropolitan Perth or far away from populated areas do not affect many people. Therefore, media attention is diverted elsewhere. This is not unique to WA: you have the same in NT, northern SA, and the west of eastern states.

This is also not unique to bush fires. Volcanoes only get media attention when they affect people: recent examples are Fuego in Guatemala or Kilauea in Hawaii. The other 50 or so active volcanoes in 2018 get close to zero media attention, because they do not affect anyone (or at least, they do not affect people that the Western media cares about).


Does the moon have any affect on earthquakes being created? Here, in New Zealand, we just had a 7.5 magnitude earthquake hit. Alot of people are saying that the super moon caused this.

I have doubts as to the super moon actually 'causing' it but could have it contributed to the earthquake due to its stronger gravitational pull?

The forces involved in the New Zealand earthquake are not amenable to precise evaluation - at least not without detailed geotechnical evaluation, but we can use the peak ground acceleration as a proxy. For a magnitude 7.5 earthquake the peak ground acceleration is about 0.4g. Compare this to the normal moon's gravitational acceleration on Earth's surface of about 3.318 E-5 g. 'Super-moons' are about 16000 km closer than usual, yielding a gravitational acceleration of 3.783 E-5 g. Therefore the differential gravitational acceleration of a super-moon, compared to a normal moon, is about 4.65 E-6 g. Or to put it another way, the effect of a super-moon is to create about a 0.001% of the acceleration (and hence force) required for the accumulated strain energy to overcome friction, and hence cause the earthquake. This assumes that all of the moon's gravity was aligned in such a way as to exacerbate strain along the slip plane - which is never going to be the case.

I suppose that one could argue that the miniscule gravitational force of a super-moon could have been the 'straw that broke the camel's back', but the accumulated strain energy in the ground must have been so great that the earthquake was about to happen anyway, with or without the moon's gravity.

Afterthought: With the boot on the other foot: The Earth's much larger gravitation has an effect on the Moon. There are moon tides which cause regular, small but measurable moon-quakes. See Moritz and Melchior (2013), Tidal Interactions in the Earth-Moon System.


Why is the outer color of a rainbow red? Why is the outer color of a rainbow red?

(Source: Wikipedia)

Rainbows are created under certain light conditions when water droplets in the atmosphere act like a prism and refract sunlight.

Light is part of the electromagnetic spectrum which covers electromagnetic waves from radio waves with a wavelength of 1000 m (long wavelengths) to gamma rays with wavelengths around 0.01 nm (short wavelengths).

Sunlight is composed largely of all the colors of the spectrum of visible light. When our eyes see all the colors at once, our brain interprets the color as being "white light".

When humans see a red object that object reflects red light by absorbs all the other colors of light.

In the spectrum of visible light, red light has the longest wavelength of 700 nm and violet light has the shortest wavelength of 400 nm.

When light enters a water droplet in the atmosphere the water droplet acts like a mini prism. The angle at which the different wavelengths of light exit the prism is determined by Snell's Law and this is why light that exist a prism, or is in a rainbow, is layered into colors with red being the first layer and violet the last.


Deriving shallow water equations: why is the vertical velocity equal to the material derivative of the surface level? I'm reading about the derivation of shallow water equations, and I have a hard time understanding why
$$ w(\eta) = \frac{D\eta}{Dt}$$
where $w$ is the vertical velocity, $\eta$ is the (top or bottom) vertical boundary of the layer and $D/Dt$ is the material derivative.
In Atmospheric and Oceanic Fluid Dynamics (2nd ed. 2017, chapter 3.1.2), Vallis gives the following explanation:

At the top the vertical velocity is the material derivative of the
position of a particular fluid element. But the position of the fluid
at the top is just $\eta$, and therefore
$$ w(\eta) = \frac{D\eta}{Dt}$$

Why is the vertical velocity at the top the material derivative?
Edit: Added a schematic illustration of the shallow layer. As you see, $\eta$ is not assumed to be constant.

This is a statement of the kinematic free surface boundary condition: there can be no normal flow through the boundary, only tangential flow along it. Equivalently, the normal velocity (relative to the interface) of the free surface position is the same as the velocity of the fluid.
Defining the position of the free surface as
$$ z = \eta(x,y,t) $$
then taking the material derivative
$$\frac{\partial z}{\partial t} +
u\frac{\partial z}{\partial x} +
v\frac{\partial z}{\partial y} +
w\frac{\partial z}{\partial z} =
\frac{D\eta}{Dt}
$$
Every term on the LHS besides $\frac{\partial z}{\partial z}=1$ goes to $0$ due to the fact that $z$ is an independent coordinate (see this answer for reference), leaving us with
$$w(z=\eta) = \frac{D\eta}{Dt}$$


What was the oxygen concentration in the air during the late miocene period? As the title says, I'd like to know what the O2 concentration was during the late Miocene period. I've tried to look this up but I'm having a hard time finding any conclusive data on it, or even any graphs of oxygen concentration on a scale smaller that 100 million years. From what I can tell it should be lower than today, although I can't tell by how much.

R. Tappert et al (2013) used carbon isotopes in ambers as proxies for atmospheric oxygen concentrations. Their work indicates an initial Miocene O2 concentration of 16% and rising to about 20% at the end:

It's pretty remarkable how different their results look from other models. Some think that some inferred upward trend in O2 levels since the Eocene gave rise to the mammals, or at least bigger brains in mammals.
Hope this helps!


What could have formed the pattern inside this piece of siltstone? I have what i think is a piece of siltstone with an interesting pattern on the face. It looks like a lichen or lightning bolt, as shown in the picture. The interior of the pattern is the same color as the stone itself, while the negative area is black. I was wondering what may have caused this pattern to form.

Interesting. The photo is low quality so I can not say for sure but possible candidate explanations are:

a septarian concretion
a fulgorite
a dendrite
a differential staining based on differences in porosity

To get a better answer please include some close-ups of the central area and some pictures of the other sides of the rock


What geology-related displays at museums, universities, etc. in California are especially well-done and enlightening? I like the rock garden and accompanying display outside the Berkeley geology building -- where else are there exhibits on rock types or on geological processes?

Alas, you live in the wrong era. In the 1960s and 1970s by far the best and most informative was the geological museum in South Kensington (West London). Sadly, it is now dumbed-down - sacrificed on the alter of children's populism. The Colorado School of Mines geology museum is reckoned to one of the best, especially for minerals. Otherwise, I can't speak for America, but if you are ever in Vienna you must visit their Natural History Museum where the mineralogy and meteorite galleries are gob-smacking superb. The Natural History Museum in Adelaide, South Australia has the world's best exhibit of Eocambrian fauna, and also boasts a spectacular opalized plesiosaur.


How does evapotranspiration affect rainfall? Evapotranspiration is when a plant evaporates water off the surface of its leaves in order to move water throughout its system with cohesive and adheisiveforces. My question is how will a sudden decrease in evaportranspiration in regions concentrated with agriculture affect the prevalence of rain in the region? For example, if crops died off in the agricultural region or if the water released via evapotranspiration was collecting in a greenhouse.

Without water in the air, clouds cannot form and evaporate quickly if they do and so a sudden drop in evapotranspiration that resulted in low humidity could decrease the prevalence of rain. But, in simulations, there's not usually much of a measurable effect (http://www.sciencedirect.com/science/article/pii/0273117787902900?np=y). This is because there's a lot more going into this than just evaporation from plants and the total amount of water that winds up in the region's atmosphere.

Air is constantly moving and there's a lot of it, and so to have a measurable impact, this would need to be a pretty large region and/or evapotranspiration would need to stop for an extended period of time.
Plants have a greater impact on their environment than what can be measured through evapotranspiration
Evapotranspiration affects energy balance, which means that sunlight also plays a role in the ultimate effects.

The result is a rather complex web of interactions and an effect that would be very different depending on season, region, and how the loss of evapotranspiration occurred. So, the two scenarios you proposed would have very different effects.


Why is it said that Amazon creates 20% of the oxygen production of the world, when it accounts with less than 14-12.8% of the forest area? Many times we see in articles that the Amazon rainforest creates 20% of the oxygen of the world . Even french president Macron stated this in a tweet Macron tweet

According to this Amazonas size Amazon size is 5.5 millions km². But according to this List of countries by forest area

World forest area is between 39 millions to 43 millions km2, depending if you believe the world forest area they give, or the added forest area of each country (which surpasses 43 millions km2) . I suppose other data is taking into account to say Amazonas create 20% of the oxygen.

Why is it said that Amazon creates 20% of the oxygen production of the world, when it accounts with less than 14-12.8% of the forest area?

I cannot find any language in peer-reviewed literature (as far as publicly accessible) that makes the 20% claim reported in the question. I therefore consider this claim to be of obscure and dubious origin.

About 50% to 55% of the oxygen produced via photosynthesis is estimated to come from the world's oceans, as reported in the following two papers:

Curtis A. Suttle, "Marine viruses -- Major players in the global ecosystem." Nature Reviews Microbiology 5 (10): 801-12 (2007)

  The oceans cover more than 70% of the Earth’s surface. They control the climate, provide a significant amount of the protein that is consumed globally and produce approximately half of the Earth's oxygen.

A. Yu. Borisov, L. O. Björn, "On oxygen production by photosynthesis: A viewpoint", Photosynthetica (2018) 56: 44

  We also find that the ocean produces 22% more oxygen than the land surface.

According to an expert quoted by the BBC, about 16% of the land-based oxygen production from photosynthesis occurs in the Amazon basin:

  A large proportion of the world's oxygen is produced by plankton, explains Professor Malhi. He says of the oxygen produced by land-based plants, about 16% comes from the Amazon.

Is this claim plausible? Based on the reported size of Amazonian forests at 6-8 million km2 and the world's total forested area of about 40 million km2, I am inclined to answer in the affirmative, although not all of the land-based oxygen production occurs in forested areas.

Yale's Global Forest Atlas:

  Amazon basin is the largest tropical rainforest in the world, covering a size approximately equal to the lower 48 United States. 6-8 million square kilometers of forest house approximately 10% of the world’s biodiversity and 15% of its freshwater.

Based on data from the FAO suborganization of the UN

  Forests cover 31 percent of the world’s land surface, just over 4 billion hectares.

The area of a forest and its oxygen production are unlikely to be in strict linear proportion to one another, as the rate of photosynthesis should depend on such factors as solar irradiation (which varies with latitude and cloud cover) and temperature (in boreal forests) or the seasons (for deciduous forest in moderate climates). The density of a forest will likewise be influenced by the availability of water and nutrients.

How do scientists estimate the amount of oxygen produced via photosynthesis? Best I can tell from a perusal of the literature this is done indirectly by estimating total biomass, which itself is determined by a combination of satellite data and on-the ground measurements. Such estimates carry a non-trivial amount of uncertainty.

Nowak, David J., Robert Hoehn, and Daniel E. Crane. "Oxygen production by urban trees in the United States."
Arboriculture & Urban Forestry. 33 (3): 220-226. (2007)

  The net amount of oxygen produced by a tree during a year is directly related to the amount of carbon sequestered by the tree, which is tied to the accumulation of tree biomass.

S.S. Saatchi, R.A. Houghton, R.C. Dos Santos Alvala, J.V. Soares and Y. Yu,
"Distribution of aboveground live biomass in the Amazon basin",
Global Change Biology (2007) 13, 816-837

  To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. [...] We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and belowground biomass, is 86 PgC with ± 20% uncertainty.


How did Earth's atmospheric layers get their names? How are atmospheric layers named once they have been discovered?

Who gave the names Troposphere and Stratosphere

The stratosphere was firstly discovered by Léon-Philippe Teisserenc de Bort and Richard Aßmann (they did not cooperate) around 1900. Teisserenc de Bort denoted that layer as 'zone isotherme' in his publication on his discovery. However, he published in French. I remember to have read somewhere - not sure where - that he gave the two names 'troposphere' and 'stratosphere' to the two lower layers after discovering the existence of a quite distinct second layer. Unfortunately, I do not find the reference anymore. In the article Hoinka (1997) you will find some information about the discovery of the stratosphere.

What the Names mean

Troposphere

tropos (greek): turn(ing)

Turbulent mixing is relevant in this layer of the atmosphere => Turbulent Mixing Sphere => Troposphere

Stratosphere

stratum (latin): something which covers something else (pavement, blanket)

This layer of the atmosphere, which is not dominated by turbulent mixing, covers the lower turbulent layer => Covering Sphere => Stratosphere

Mesosphere

mesos (greek): middle
This part of the atmosphere is the third of five (from humans defined) layers of the atmosphere => Layer in the middle (not by distance/height but by counting layers) => Mesosphere

Thermosphere

thermos (greek): warm, heat

This layer can be heated to above 1000 °C by the sun. However, it does not feel 'warm' because of the low 'air' density. => Heated/hot layer => Thermosphere

Exosphere

éxo (greek): outside, external

This layer is the most outward located layer of the atmosphere. => At the outer side located => Exosphere


Fissure Energy/Force Equation For this, I am trying to understand if it is a measure of force (Newtons) or energy (Joules ) of when fissures are created, Fissures are where the ground is being torn up either by volcanic ventilation, or otherwise.

So whether it is measured in force or energy, I wish to know what is the best equation for this phenomenon to occur.

So the information I have that would further this is the area is 20.58 m^2, the depth is 30,000 m. and it happened in just a second.

I thought it would be used for Tensile Strength with Silicon with the yield strength of 180 MPa.

Force is used to (try to) move objects apart. Energy is expended as the objects move and thereby separate. In a pure physics sense, until an object moves, absolutely no work energy is expended. You can push on a wall all you want with as much force as you want but, unless the wall moves, you do no work.

A stress-strain curve of a materials is a map of force to cause a deformation. The area under the curve is a map of the energy to cause the deformation. Up to the yield stress, the area is resilience. This is the energy expended to cause elastic deformation of the material. Because the stress strain curve is a straight line in the elastic region, the functional form of resilience $R$ is

$$R = \sigma_y \epsilon_y / 2 = \sigma_y^2 / 2E $$

where $\sigma_y$ is yield stress, $\epsilon_y$ is yield strain, and $E$ is Young's (elastic) modulus.

A further stress-strain function happens up to breaking. The total area under the stress-strain curve to break is toughness. The stress strain curve is not linear in this region. Integration methods are required.

The fissure forms because the material breaks, not because it reaches the end of its elastic deformation. The force needed is the obtained from the true breaking stress of the material. The energy required is obtained as the toughness of the material.

Ductile materials have a yield, a tensile, and a breaking stress. The tensile strength is the point where the material begins to neck. Think chewing gum stretched ... necking is where the gum thins.

Perfectly brittle materials have no yield. They just fail after elastic deformation. The toughness is the resilience in this case.

Many cases for materials that show only modest if any ductility and no necking assign the yield stress as the failure stress and ignore breaking stress. The toughness is greater than resilience, but the distinction is not a hard one.

Resilience and toughness may appear to have the same units as stress (e.g. Pa = N/m$^2$). In reality, a better unit designation for both is energy per unit volume (e.g. J/m$^3$).


Difference between "Geology" and "Physical(Natural) Geography"? I know "Geology" is a branch of "Natural sciences" and is for studying natural and physical phenomena related to earth. But "Physical Geography/Natural Geography" seems to study exactly the same thing. What is the main difference between these two fields of study?

Physical Geography is a wide area of study - there is many sub-disciplines in this field, such as Biogeography, Climatology, Hydrology, Pedology, Geomorphology (and others as well). Often the scale interesting for the physical geographer is the recent past and future, calculated in thousand of years before today up to a few million (time scale could vary in the recent past (last few years and up to the glaciations and Pleistocene at large). Further, it is focused on surface processes, and not necessarily on rocks, there is a lot more interest in dirt, soils, looses pebbles, and their dynamics of erosion and deposition, the processes affecting the surface. A physical geographer will enjoy hunting for deposits exposure when in the field, so a wall of ancient dirt stratae.

On the other hand, the Geology field is interested in longer period of time, in rocks, often very deep rocks, the internal geodynamics (mantle, core, magma), will consider the disposition of crystals, petrology, geochemistry of rocks. Otherwise, geologist will be interested in the same topics that physical geographer do, but will use different tools, or consider those topics as a factor among many. Geologist may be mingling with the engineering world better than geographers. They will hunt for outcrops in the field, like intact, in situ rocks that can explain something about the site.

To illustrate this, when I go in the field with geologists, I prefer to bring a shovel, they bring a hammer (I bring one too but will choose the shovel over!). We will enjoy the accessibility to a drill to make boreholes, but will be happy with the first 5 meters depth where they would be interested more in deeper drilling. Further, I will be glad to drill in soils and dirt, where they would definitely prefer in rocks.


What is the deepest we have ever gone into the Earth? I remember Journey to the Center of Earth and wonder: What is the deepest in the Earth surface or below sea level we have traveled either by foot, sub, drill or camera?

Probably a bit over 4 km, in this South African mine: https://en.wikipedia.org/wiki/Mponeng_Gold_Mine  But as the link mentions, the mine operators go to considerable lengths to reduce the mine temperature to endurable levels from the  66°C/151°F of the surrounding rock.

Note: This answer is for the original question, where the OP asked for the deepest depth below the surface.  It's since been changed to ask for depth below sea level.

http://cracked.tumblr.com/post/162183647834/the-mponeng-gold-mine-in-south-africa-is-the


How important is understanding linear algebra in groundwater modeling? I am considering taking a course in linear algebra and wanted to get a survey to see how important it is. My goal is not just to understand how to push the buttons in some software (e.g. GW Vistas, Aquiferwin32), but to really understand how groundwater modeling works.

Relatively important, depending on the basic principles of the modeling you are interested in, and to what extent you want to get yourself involved in it.

In many areas of computational geophysics, e.g. atmospheric, oceanic, hydrological modeling etc., there are modelers, modelers, and modelers. First group of modelers get model output from somebody else, do some analysis, make some plots, and write about what they found. Then, there are modelers who design their own experiments, play with tunable parameters, maybe even change a few lines in the code and run the model. Finally, there are modelers - these spend most of their time on building and improving models, both in terms of numerical methods and software design. They could go for few years without publishing a single paper, but boy did they work hard.

If you are interested in computational science aspects of modeling, i.e. the inner workings of the model and how to improve it, understanding linear algebra as well as numerical methods will prove to be very valuable. While it is likely that you will never end up having to implement that matrix inversion or sparse matrix multiply yourself, and instead use one of many well documented production libraries, it is important to understand how they do it and why they do it in a particular way. From my own experience, I can say that most of the time it won't matter, but sooner or later there comes a situation where having knowledge about how low-level operations work will save you from pulling your hair out for weeks.

And this does not go only for linear algebra - I would extend this advice and urge you to strive at also understanding differential equations, discretization, computer architecture, floating-point arithmetic.


Giem's article on carbon dating I don't want to start any controversy. I'm just curious about what could professional geologists say about this paper, and what is it's current scientific status, since I couldn't find any serious discussion about the subject online.

The paper is the following, by Paul Giem:

http://www.grisda.org/origins/51006.htm

It is told that the amount of carbon 14 that he found on diamonds and other fossil samples is impossible from the viewpoint that these samples are millions of years old. Were his finding subsequently discussed or disproved?

The cited paper, and ones like it, are young earth creationist nonsense. The Geoscience Research Institute is an arm of the Seventh Day Adventists, whose official position is that "in a recent six-day creation the Lord made “the heavens and the earth, the sea, and all that is in them” and rested on the seventh day." This is a central tenet of Seventh Day Adventism (it's in the very name of the religion); teaching or writing about an Earth that is billions of years old is explicitly forbidden.

Young earth creationists are wont to attack radiocarbon dating because it has significant limitations. Samples can be contaminated in situ, during extraction, during storage, in transportation, and in processing. Contrary to Giem's claim that "the hypothesis that machine background can account for this carbon-14 has been universally rejected by researchers in the field, and for good reason," several of the papers cited by Giem were scientists trying to assess the machine background and other limitations of their techniques.

For example, Giem cited Aerts-Bijma et al. seven times. This paper looked at "AMS sample handling in Groningen." This lab attempts to perform radiocarbon dating in an automated, assembly line fashion, taking about an hour to perform an analysis. This is fine for archeology studies with budget constraints. The paper by Aerts-Bijma found their approach has limits.

One issue with carbon dating is that the previous run can contaminate the next. To test this, Aerts-Bijma et al. ran two sets of tests against the same sample of anthracite. In one, they interspersed each measurement by carbon dating 100% modern carbon. This gave an artificially high carbon-14 reading for the anthracite. In the other, they didn't do such a dumb thing and found a lower floor. Giem reported the intentionally mishandled reading.

Other labs have lower floors by following more stringent but significantly more expensive procedures. Carbon compound scintillators such as those used to detect neutrinos need carbon that has extremely low amounts of carbon-14. The best source of such carbon is old hydrocarbons that have not suffered in situ contamination. Techniques have been developed to measure carbon-14 to one part per 1018 to ensure that those sources are indeed old and uncontaminated. These techniques are well beyond the budget of a typical archeological study. Giem did not report these because they go against his claims.


The edges of the tectonic plates I have read that the edges of the tectonic plates exist at places like: huge mountains and sea trenches, and I wondered if they exist at the mid-oceanic ridges?

The short answer is yes, the edges (boundaries) of tectonic plates do occur at the mid-oceanic ridges, such as the Mid-Atlantic ridge.

There are three types of tectonic plate boundaries:

Transform Boundaries where the plates slide past each other sideways, such as at the San Andreas Fault.
Divergent Boundaries where the plates are moving apart, such as the Mid-Atlantic Ridge  and the East African Rift.
Convergent Boundaries where one plate slides beneath the other plate, such as the Andes mountain range & the Japanese island
arc.


Pyroclastic flow protection Related to the question Why don't scientists use fire entry suits to study volcanoes?, where the issue of volcanologist protection against lava splatter and bombs is discussed.  Another major and sometimes sudden volcanic event are pyroclastic flows - the suddenness and swiftness of these events have occurred in many places, one recent example is the recent tragedy that occurred at Mt. Ontake, Japan, discussed in the question Why would volcano eruption cause cardiac arrest?.

There are many examples of volcanologists perishing due to pyroclastic flows.

Around some volcanoes in Japan, for example, there are reinforced concrete shelters touted as being pyroclastic flow shelters, as shown below on Oshima Island:

Image source

From personal experience, these shelters also surround Mt. Asama (have visited there).

How effective are these concrete shelters for survival against pyroclastic flows?

additionally, has there been any research for the development of protective gear against pyroclastic flows?

Pyroclastic flows have often been considered to be by and large, unsurvivable, especially since the devastation in 1902 of St. Pierre on Martinique, many fatalities are due to hypoxia and severe thermal injuries (Hansell et al. 2006; Baxter et al. 1998).

According to the USGS webpage about pyroclastic flows, these events can occur very suddenly, without much warning at all (e.g. Mt. Ontake) and travel fast, and can be several hundreds of degrees Celsius. Pyroclastic flows also contain considerable amounts of toxic gases and rock fragments.  The presence of water bodies in the path can result in lahars and mudflows.

As pyroclastic flows are variable in nature and can be sudden, there is no one-way of volcanologists protecting against its effects, except to get out of the way (if possible).  The use of fire suits will limit mobility and still may not protect from the flow itself.

In the AGU blog So you want to be a volcanologist?, Jessica Bell, a volcanologist from the USGS makes the point that being prepared is crucial for greater chances of survival, emphasising the point of 'doing your homework' about the eruptive history of the volcano before going to the volcano.  Gas masks, gloves, long sleeves and long pants are also crucial.  Critically, a volcanologist must be:

  very careful to avoid areas that could be dangerous – within the path of pyroclastic flows or mudflows or lava bombs, near gas vents or lava flows, or unstable ground are just a few.

It should be noted that several media reports mention that not all volcanoes have these kinds of shelters.

But where the shelters are present, they could provide an obstacle that could affect pyroclastic flow propogation but only when the shelter is distal to the eruption and if the flow does not last too long, related to modelling performed by Todesco et al. (2006) and earlier by Baxter et al. (1998) who assert that this situation is survivable.

Baxter et al. (1998) also state that through their models, the most effective shelters can shield against the dynamic pressure and heat transfer associated with a pyroclastic flow, especially if the flow is of short duration.  This effectiveness obviously diminishes when the flow lasts a considerable amount of time, is large-scale or the shelter is too close to the eruptive source.

What these shelters won't protect from is fine ash dust, and not everyone sheltering will necessarily have a gas mask (as per the volcanologist above).  Another problem with this, as noted after the Mt. Unzen eruption of 1991 is that even if shelters are spaced evenly apart - time is a major factor - the time to reach the shelter against the time it takes for the pyroclastic flow to reach that location.

A lot of shelters around some volcanoes that have had a past history of pyroclastic flows have 'exclusion zones' with the shelters in the distal regions of previous eruptions, this method of exclusion zones is claimed by Hansell et al. (2006) as being one of the only effective protective measures from proximal effects of an expected pyroclastic flow - which also describes, alongside the modelling by Baxter et al. (1998), the way that these shelters can have any effectiveness by being in the distal regions.

References

Baxter et al. 1998, Physical Modelling and Human Survival in Pyroclastic Flows, Natural Hazards

Hansell et al. 2006, The health hazards of volcanoes and geothermal areas, Occupational Environmental Medicine

Takahashi, 2007, Unzen-Fugendake Eruption Executive Summary 1990－1995, Unzen Restoration Project Office,
Kyushu Regional Construction Bureau,
Ministry of Land, Infrastructure and Transport

Todesco et al. 2006, Pyroclastic flow dynamics and hazard in a caldera setting: Application to Phlegrean Fields (Italy Geochemistry, Geophysics, Geosystems


What rate of deforestation would be needed until we run out of oxygen? I was wondering about how much unchecked deforestation would have to occur before we tipped the balance and started using more oxygen than was being replenished by plants and trees.

Last I heard it was estimated that every day an area the size of Wales was being removed globally which sounds like a very large amount. This could be inaccurate now as it was a long time ago. Many companies now plant trees to offset carbon footprint or whatever but assuming they didn't how long would we have?

My question could be reduced to this - what area of land would need to be covered by forest to sustain life on earth without us all suffocating?

I imagine that this is a very simplistic view, it would probably cause global warming to accelerate first or the ecosystem to collapse and we'd all starve. I should say at this point that I am no scientist!

As Jan points out, there are many other factors in the oxygen balance, not just trees. But for a bit of fun, let us suppose that we burn all the trees on the planet. The global biomass of carbon is estimated as 47.4 PgC (it varies a bit according to season and inter-annual growth conditions). Of this we can estimate that the contribution from trees is about 36.3 PgC. 1 tonne of carbon consumes 2.67 tonnes of oxygen to create CO2, so the oxygen consumed is about 9.68 x 10^^10 tonnes. The total mass of the atmosphere is known to be 5.15 Petatonnes, of which oxygen is 20.95%, or 1.08 Petatonnes of oxygen. So taking the ratio, the loss of atmospheric oxygen from burning all the trees is 0.0034%. This is far less than the day-to-day fluctuations in available oxygen due to changes in atmospheric pressure - i.e. the weather.

So, there is a lot of woody biomass, but think of the partial pressure of the oxygen layer that wraps the Earth: 21.2 kPa O2 on every square centimetre of the Earth's surface. We are never going to run out of oxygen! On the other hand, pyrolysis of every tree on the planet would create so much smoke that we would probably all die of lung cancer!


What is the difference between climate change and global warming? 1. Question:

In the article, Global Warming vs. Climate Change is an example of the confusion regarding these terms.

What are the "official" definitions of "Climate Change" and "Global Warming"?

How does the IPCC - distinguish between "Global Warming" and "Climate Change"; or, are the terms interchangeable?

Clarification:
To avoid "opinion" / "debate", I am just hoping for authoritative definitions. Specifically, I am hoping to clarify the different uses seen in objections raised within the science community, (Question Link).

2. Example Ambiguities:

Global Warming - a relentless rise in temperature? Due to both natural and human contributors?  Or exclusively to pollution?  Associated with the relentless rise in Carbon Dioxide levels, or perhaps Chlorofluorocarbons, etc.
Climate Change - A competing theory? A newer refinement of Global Warming Theory? Extreme, and unpredictable variability in climate--rather than a consistent, relentless increase in heat.
Corollary Theories -  Is Climate Change is a larger study, and Global warming falls within, or one causes the other, etc?

Is "Climate Change" a derived theory within "Global Warming", or vice versa?
  Is "Climate Change" a reiteration of an earlier theory, "Global Warming"?
  Are these terms in fact synonymous?

In order,

Vice versa.
No.
No.

"Climate change" (and its kin, "climatic change") is a far older term than is "global warming." The terms "climate change" / "climatic change" are and always have been the dominant terms used in the scientific literature (over "global warming"). Anthropogenic global warming is but one aspect of anthropogenic climate change, which in turn is but one aspect of climate science. In particular, increased global warming (above natural) is one of the climatic consequences of humans dumping very large amounts of greenhouse gases into the atmosphere.

Since climate change is the older concept, climate change cannot have derived from "global warming", and it is not a reiteration of an earlier theory.

Some references that show that "climate change" is an old term:

Ellsworth Huntington (1917), "Climatic change and agricultural exhaustion as elements in the fall of Rome," The Quarterly Journal of Economics (1917): 173-208.

Richard Joel Russell (1941), "Climatic change through the ages," Climate and Man, U.S. Department of Agriculture: 67.

Edmund Schulman (1956), "Dendroclimatic changes in semiarid America," University of Arizona Press, Tucson Arizona.

NASA - What's in a Name? Global Warming vs. Climate Change

Update
There was a lot of discussion on this topic. That discussion may eventually vanish. The question ended up asking for references, lots and lots of references. I do not have the time or the inclination to do that. What I can do is supply links to sites that do supply those references:

David Appell, "Some Early and Important Works on Climate Science, Carbon Dioxide, and Human Influence."

American Institute of Physics, "Bibliography by year: The Discovery of Global Warming."

Intergovernmental Panel on Climate Change, "Fifth Assessment Report."


Are Indonesian 2018 earthquakes related? Indonesia had multiple major earthquakes this year

A series of earthquakes in Lombok between July and August, including a 7.0 mainshock
The 7.5 earthquake + tsunami in Sulawesi, September 2018
A 6.0 earthquake near Java, on 11 October 2018

I'm aware that Indonesia sits in an earthquake zone, but historically I don't think so many big ones occur in such a close time. Also, this spread out in different islands (e.g. the epicentres in Java and Sulawesi are ~1,000 km apart) over several months, so it doesn't look (at least to me) like typical mainshock-aftershock relationship. Were they related in some way? e.g. Do they indicate an increase seismic activity in the region?

I'll try to answer your second question using the earthquake catalog of the USGS. I encourage you to run your own queries, it's pretty fun and easy to use!

Here is a result of a query for 6+ magnitude earthquakes, starting from 2000, centered around the indonesian archipelago. There is a total of 435 events in the region during this period of time. Now you can download the list as a csv file and have a look at it to get some statistics.

If you sort the events by year, you'll see that there are between 11 (in 2017) and 35 (in 2007) events per year, with a mean of 21.75 events per year. It's hard to get a clear tendency from this graph, although it seems that there was a decrease in activity in the 2011-2018 period.

It gets clearer if you look only at 7+ earthquakes. In this period there are 54 events in the region, but you can see that the vast majority happened in the 2000's, culminating in 2010 with 8 events. Then there is the only year without a 7+ event (2011), and five years in a row with only one event per year. From this graph it also seems that there is an increase in the last two years, with already 3 events in 2019, but I would be careful interpreting this: we lack perspective, and 54 is quite a low number to do a statistically robust analysis.

So from this I'd say there might be an increased seismic activity in the region, although it's too soon to tell for sure. Only time will tell, unfortunately.

Edit: The first question is beyond my competence. It is known that earthquakes redistribute the stress in the lithosphere (see the review by Hardebeck & Okada, 2018). But the tectonic setting is really complicated in Indonesia, with lots of small plates and some unique features, like the divergent double subduction in the Molucca sea (Zhang et al., 2017)... So it's hard to tell if an earthquake here could trigger an earthquake there by modifying the regional stress field.


How far downwind of a covid-19 emitter has a 1000-fold reduction in PPM? How far downwind of a covid-19 emitter has a 1000-fold reduction in PPM?
Assuming that covid-19 (0.12μm diameter) particles have the aerodynamic properties of a gas:

Particles < 20 μm behave same as gas – Low settling velocity
http://home.engineering.iastate.edu/~leeuwen/CE%20524/Presentations/Dispersion_Handout.pdf

How far would someone have to be downwind of a covid-19 particle emitter for an at least 1000-fold reduction in PPM?

As I said in my comment, viruses aren't my area (concerning units). But the answer is actually unitless. The exact answer you seek is dependent on a couple of different variables:

The speed of the exhalation (cough or breathing)+speed of wind
The atmospheric stability

Of course, the viral load of the exhalation is also important, but since you're asking for a ratio, I won't list that.
The Gaussian Plume model can be used to describe pollutants. The Gaussian Plume model is: $$\frac{C}{Q}=\frac{1}{2\pi U \sigma_y \sigma_z}\exp\left(-\frac{1}{2}\left[\frac{y}{\sigma_y}\right]^2-\frac{1}{2}\left[\frac{z-H}{\sigma_z}\right]^2\right)$$,
where $C$ is the concentration, $Q$ is the emission rate, $U$ is the wind speed (or worst case-scenario is cough speed), $x$ is the downwind distance, $z$ is the distance from the ground, and $\sigma_x, \sigma_z$ are the horizontal and vertical diffusion constants.
$\sigma_y, \sigma_z$ are functions of stability and wind speed. The actual formulas are... iffy. Theoretically they can be described as $$\sigma_{y,z}=\sqrt{\frac{2K_{y,z}x}{U}}$$, where $K$ is the eddy viscosity. There are empirical formulas based on stability classifications too.
Lets assume that the receiver is directly downwind and at the same height (z=H and y=0). Therefore the equation collapses to: $$\frac{C}{Q}=\frac{1}{2\pi U \sigma_y \sigma_z}$$. Since the distance downwind is expressed only by $\sigma_{y,z}$, then to answer your question, we need to isolate $\sigma_{y,z}$. $$\sigma_y \sigma_z=\frac{1000}{2\pi U}$$
Let's just say, for the sake of argument, consider two different scenarios:

Empirical $\sigma_{y,z}$ (refer to this for values of constants)

$$(ax^b)\times (cx^d+f)=acx^{b+d}+afx^b=\frac{1000}{2\pi U}$$
And this is complicated to solve. So I'll leave solving for $x$ as an exercise to the reader.

Constant $K_{y,z}$

$$\sqrt{\frac{2K_{z}x}{U}}\sqrt{\frac{2K_{y}x}{U}}=\frac{1000}{2\pi U}$$
$$\frac{4K_{z}K_{y}x^2}{U^2}=\left(\frac{1000}{2\pi U}\right)^2=\frac{10^6}{4\pi^2U^2}$$
$$x=\sqrt{\frac{10^6 K_{z}K_{y}}{16\pi^2}}$$
$$x=\frac{10^3}{4\pi}\sqrt{K_{z}K_{y}}$$
If we assume that $K_z=K_y=K$, then the equation simplifies further. $$x=\frac{K10^3}{4\pi}$$
There are many ways on how to calculate $K$. One simple formula for $K$ can be used if mixing length theory is invoked
$$K=\frac{ku_*z}{\phi(\frac{z}{L})}$$, where $k$ is the von-Karman constant, $u_*$ is the friction velocity, $\phi_M(\frac{z}{L})$ is the Businger-Dyer function for momentum, and $L$ is the Monin-Obukhov length. If we assume neutral atmospheric stability,$\phi_M(\frac{z}{L})=1$ and the resultant equation can be written as:
$$x=\frac{ku_*z10^3}{4\pi}$$
More assumptions! Let's assume z=1.5 m and $u_*=1.11$ m s$^{-1}$ (corresponds to a 5 kt wind speed at 10 m with a roughness length of 0.1 m under neutral stability). Plugging those numbers in gets
$x=35$ m
Of course, there were a LOT of assumptions to get to this point. But this is what I have to offer.


What is the "forecast hour of product" The NCEP website describes the file naming format of the GFS forecast data.

https://www.nco.ncep.noaa.gov/pmb/products/gfs/

What does "forecast hour of product" mean?

The forecast hour of the product is the hour after the model cycle runtime that the forecast is valid at. For example, if the the cycle runtime is 12Z and the forecast hour is 9, then the the forecast is valid for 21Z. If the cycle runtime is 6Z and the forecast hour is 48, then the forecast is valid at 6Z two days later.


Atmospheric conditions needed that blocks all bright light during sunsets and allows you to stare directly at the sun Today (July 5th, 2019 just before 8 pm KST), along the Han River in Seoul, the surface of the sun could be viewed with my naked eye (no protection needed), and this was safe on the eyes. It appeared much redder and it wasn't bright at all. Also, there was no visible "fog" that blocked the view of the sun in my vicinity.

I am curious about the conditions needed to create this phenomenon A possible use-case of an answer could mean the possibility to better predict when I should go view the sunset over the Han River in Seoul. It's beautiful!

Past Related Topics

Why can I look directly at the sun during a sunset but not at noon?

This is different from my question as, while you can still look at it, it is still slightly harmful to your eyes. It can still create some visual artifacts in your vision after you stop staring for even a few seconds.

The sun I saw today at sunset was not bright at all. You could stare at the sun for minutes, tens of minutes, etc without any visual impairments. Also, the sun was red in color.

There appears to be at least one more additional condition needed to produce the visual I saw today.

My Thoughts

Just to be clear, this seems to go beyond the physics of the standard sunset. To me, there seem to be 3 atmospheric conditions that are playing their part in this phenomenon. The first 2 will give you the standard sunset with its beautiful colors.

Rayleigh Scattering.
The longer distance light travels along the Horizon.

This enhances Rayleigh Scattering and gives the colors of the sunset.

???

Either this enhances Rayleigh Scattering more along the horizon (enhances #2)
Or it's a separate phenomenon completely

When combined with #1 and #2, allows people to view the surface of the sun without protection!

More Background Information

I have seen this phenomenon a few times before in Seoul.

Phenomenon never occurred in the US in my hometown for me

Hometown is farther north than Seoul.
Harbin, China would be a similar latitude.

I have never seen this phenomenon during the winter.

It's possible it has happened, but I didn't see it!
It's only occurred in the Spring and Summer for me.

While the afternoon was thicker in air pollution, I believe around sunset the air pollution nearby was much more clear.

Around this time (if UTC conversion were correct), there was a thicker air pollution mass around China and the northern part of the Yellow Sea.

Sun sets in the West, and any air conditions to the west could affect the sunset.
Is that in line-of-sight? Did the air pollution reach higher in the atmosphere around China? With line-of-sight, that would be around 10 - 60km in the air over the Yellow Sea and China.

Analysis

With #1 and #2 directly above, the longer distance that light travels along the horizon during (1) the sunset and (2) the winter in the Northern Hemisphere doesn't seem to play a big part. Otherwise, I should see this a lot in the winter around sunset. I don't, and I never have.

Can air pollution be clear nearby, yet block all the bright light rays farther away?

Photo

Here is a photo that can help show the conditions that were present at the time.  Please note that the sun appears much brighter in this picture than it was in-person. The sun was actually really dull red. As you can see, there were clouds, but I am trying to find maps that show the cloud coverage around that time, as I don't believe it was thick.

I am familiar with this phenomenon. In London, in winter 1947, I remember being able to see sunspots with the naked eye. The sun was very orange, like the one in your photo. The reason I was able to see sunspots was,of course, that the London sky was polluted with fumes and the winter sun was low on the horizon, so the rays had a greater thickness of atmosphere to penetrate. Much of the short wavelengths were filtered out, while the longer, redder wavelengths were able to get through. Much the same thing seems to have happened when you took this photograph of Seoul. It is common knowledge that red wavelengths penetrate foggy or hazy atmospheric conditions better than shorter wavelengths.


History of the Arctic Ocean Much of the Arctic Ocean is fairly shallow compared to other oceans. There must have been times in the past during severe ice ages that a lot of what is now the ocean bed was above sea level. When was the last time that most of the arctic Ocean floor was above sea level? Going back further, were there ever forests, peat bogs or coal deposits on the present day ocean floor, and when were the internationally coveted oil reserves formed?

During glaciations, the shelves down to ~100m depth would have been above sea level, but they would have been covered by ice sheets.

Geology.com
The actual "ocean floor" would still be deep water.
There is a general explanation of the oil formation here and here, although they don't say when (or where the continents were when the sediments were deposited), and again, this is on the shelves, not the floor.

"An overview of the petroleum geology of the Arctic" has:

  Maps of palaeogeography of the Arctic based on Golonka's maps for the Late Devonian, the Middle Triassic, the Late Jurassic and the Middle Palaeogene, representing the times of deposition of some of the major Arctic source rocks


Required temperature difference between land and sea for sea breeze What is the required temperature difference between the sea and the land in order to create a sea breeze? Is there any relation between the temperature difference and the sea breeze intensity? Is there any relation of wind intensity with the rate of increase or decrease in temperature difference?

So wind is caused by differences in atmospheric pressure which in turn is a result of temperature induced density differences.

1. Required temperature diference:

A quick search brought up this paper:
Miller et al. 2003 SEA BREEZE: STRUCTURE, FORECASTING, AND IMPACTS https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2003RG000124

They calculate that a 10 degree difference between land and sea over 20km results in an accelaration of 7.2*10E-3 m/s. Now, this is an estimate. There are many more variables that will affect the complex fluid dynamics of the system.

2. Wind Intensity vs dT.

Absolutely if you increase the temperature gradient (difference) the wind speed will be higher.

from the paper they mention the sea breeze of Alcoa Bay, South Africa, where the strongest sea breeze occurs in areas with nearby dune fields:

  "During the daytime the sand dunes create a region of superheated air immediately overhead, setting up a very strong land-sea temperature difference."

3. Wind Intensity vs dT/dt

Now this is where it gets complicated. So thinking of this in a mathematical sense, the rate of increase in temperature is not going to matter that much because when calculating the wind speed at a given time what matters most is the absolute temperature difference between land and sea.
  For a temperature difference to occur the rate of temp change has to be fairly rapid as the system is always trying to reach equilibrium (i.e. remove the temp difference). So naturally if you have a parcel of air, it will reach a higher temperature if the heating is fast vs slow. If it reaches a higher temperature then it will result in a greater wind velocity. But if you wanted to make a more complex model of the system then you would need to look into the rate of change of change in Temp.


Is cloudfraction a proper measure of gaseous data expanse? I was working with SO2 column data product from https://disc.gsfc.nasa.gov/datasets/OMSO2_003/summary?keywords=OMI%20Total%20Column%201-Orbit%20L2%20Swath
I wanted to know, is the cloudfraction data in SO2 column an accurate measure of the Sulphur Dioxide present in an area?

No, cloud fraction is not a good measure of $\ce{SO_2}$. Clouds are functions of moisture, temperature, and cloud condensation nuclei. Som of the other variables, such as (but not limited to) ColumnAmountSO2 or ColumnAmountSO2_TRLare better indicators.


Is the weather of Miami, Florida and the weather of Lagos, Nigeria the same I've been to Lagos and it rains a lot sometimes overflooding but it's pretty sunny. I'm aware that it rains a lot too in Miami. Is the climate the same apart from Lagos being near Equator and ITCZ region?

Lagos experiences a tropical savanna and Miami a tropical monsoon climate. Rainfall and temperature are indeed not too different in the two cities but - as their different climate classifications imply - the annual cycles as well as the underlying drivers in these respects do differ (Figs. 1,2).
Although located in the Northern Hemisphere, temperature in Lagos is lowest in summer when the Intertropical Convergent Zone (ITCZ) migrates over the region and the associated cloud cover effectively blocks sunlight (https://en.wikipedia.org/wiki/Geography_of_Nigeria#Temperature). The rainfall annual cycle is again dictated by the seasonal evolution and latitudinal migrations of the ITCZ.
A more typical temperature annual cycle is evident in Miami with a maximum in summer. Rainfall in Miami exhibits peaks in June and September (as in Lagos; interestingly) mostly associated with the formation of thunderstorms that are driven by large summer insolation (leading to unstable air), moisture supply, and the favorable interaction between the subtropical high and the local sea breezes (https://www.weather.gov/tbw/Thunderstorm_Climatology).

Fig. 1: Annual cycle of rainfall (bars) and daily min/max temperature (blue/red lines) in Lagos, Nigeria (https://worldweather.wmo.int/en/city.html?cityId=258)

Fig. 2: As in Fig. 1, but for Miami, USA (https://worldweather.wmo.int/en/city.html?cityId=267)


Is there value in using a model that fails at validation against measurements? Say we have a model that describes a physical or dynamical system, for example, a hydrological model. If the model results do not match the measurements of the quantity being simulated, i.e. the model validation fails, is there any value in using the model for some other case or application?

The late George Box famously said:

  All models are wrong. Some models are useful

All models are wrong.

That's important.

All models are wrong.

In any real-world system that we're interested in, the only accurate model of the system, is the system itself. Anything else, any simplification, gives wrong answers.

Some models are useful.

That's important, too.

Some models help us structure our discussions of the uncertainties (H/T Prof Neil Strachan)

Some models allow us to test "what if" scenarios, and look at what the relative changes might be. Now, in the real world, exogenous influences that the model can't account for, would mean that the actual outcomes would be different: but if the model gives a near-enough account of the scale of relative changes, we can still make informed judgements on the basis of the models. Even when it involves pesky things such as turbulence.

Some models give us insights into emergent properties of systems: a lot of the really interesting problems are emergent properties that aren't necessarily obvious from just looking at the basic rules of the system, and any insights we can gain are valuable.

Some models allow us to do experiments on systems that we couldn't possibly experiment on. And although we know the models are wrong, they can at least give us an indication of the range of possible outcomes.

That's not to defend the use of bad models to do bad work. There's far too much of that in my field, and I do not like it. As Simon W says, it is possible to test models to see if they are suitable for a particular purpose. To continue using a model for a purpose where it is known to be inapplicable, is charlatanry, not academia.


How to understand the sentence below about rapid or fast exchange between vapour and droplet? I read an article about atmosphere and the article has this sentence:

  At all events, however, they will cause an exchange of water molecules
  between the vapour and the droplet. If this exchange is extremely
  rapid, the O18-abundance in the droplet must correspond to that in the
  surrounding vapour. Whereas if the exchange is extremely slow the
  O18-abundance in the droplet will correspond with that of the vapour
  at the place where the droplet was formed, i.e., because of the
  oblique movement of the droplet, at a considerably lower level of the
  front.

Can you tell me what is the difference between rapid exchange and slow exchange? In these two circumstances, the O18-abundance in the droplet always correspond with that of the vapour.

The wording is not clear, but here is what I understand:

In case of extremely rapid exchange of molecules between the droplet and the surrounding vapour, the droplet gets the same O18 abundance as the vapour because they reach equilibrium.

In case of extremely slow exchange of molecules between the droplet and the surrounding vapour, the droplet keeps the O18 abundance that the vapour had where the droplet was formed. This is a different location (lower in the front, as shown by figure 2), so the abundance can also be different.


Amount of Earths water with consideration to space travel? Everyone always says that there has always been, and always will be, the same amount of water on planet Earth.

What about space travel?

They obviously need water in space, so they must take it up with them. Take the International Space Station: astronauts must survive up there for around 6 months. And yes, I know they have ways to recycle it, but it must eventually be "refreshed".

I know that it makes the only teeniest, smallest of differences (a few hundred gallons taken from billions of gallons), but could that phrase be proved wrong?

Thanks in advance!

Note: I put this on the Earth Science SE because I couldn't find anywhere else it would fit.

Everyone always says that there has always been, and always will be, the same amount of water on planet Earth.

Your premise is wrong. The surface and atmosphere of the Earth keeps gaining and losing water all the time. I have no idea where is that coming from, but no scientists say the amount of water is constant.

The Earth's atmosphere is leaking gas to space. This includes mostly hydrogen gas, which is a major component of water, and also some minor amounts of molecular water.
Earth is gaining water (and a bunch of other stuff) from meteorites and dust hitting the Earth. Dust accounts for the majority of the mass flux to the Earth.
The Earth's surface and atmosphere are getting huge amount of water from volcanic eruptions. H2O is the major component of volcanic gas in most volcanic eruptions.
Earth is losing water to the mantle in subduction zones and in lithified sediments.

All of these water mass fluxes are orders of magnitude larger than the amount of water carried to the international space station. It's like asking whether you can deplete a beach from sand by taking single sand grains out of it, when you're gaining and lose huge amounts of sand by ocean wave action.


Simulating rainy weather I want to test some 3D weather radar software by simulating rainy weather. I want some degree of realism in the sense that it simulates rain systems and their boundaries and also simulates rain rates over their volumes. Weather systems should be dynamic in the sense that they can evolve and change at typical rates.

I would be satisfied with a statistical model if that's possible, rather than one driven by solving differential equations, based on my assumption that generating random numbers is easier than solving large systems of equations.

The model should be capable of running for long periods of time (a few hours of simulated real time) while generating an assorted set of weather patterns (clear weather and various levels of rain intensity). It should be suitable for real time simulation of the radar software, so weather development over time is an important requirement.

Being able to support real-time simulation is another reason I am leaning toward any more simplistic (by arguably reasonable) model.

I don't know where to begin finding a model like this. The models I have seen appear to be more complex than I would like, and probably not really suitable for my limited requirement.

What would help me is to identify any existing models that might be used for this purpose or any literature that describes how to create a model like this.

The problem with a statistical model is the reliance on dynamical model input, plus the requirement of climatology. A statistical model will also only give data for a solitary point, not an area. The simplest statistical model is persistence, which is the current weather, followed by climatology. Both are the lowest in forecast skill.

For a dynamic model, try using the WRF model (http://www2.mmm.ucar.edu/wrf/users/download/get_source.html).

It is a commonly used model. The runtime will range, depending on your computational power and needs. A larger domain will take longer, and require more. I know people who simulate hurricanes with it, and people who run fine scale modeling.

I can run WRF with a 200 km domain size for a 36 hour forecast in 1-2 hours.

Again it will really depend on your resources. Running WRF may require compilers you do not have access to. You can develop the visualization software after you ran the model, with whatever tools you find. Python and NCL are good languages, but MATLAB and a variety of other languages can be used.


Fossil from North Norfolk coast, UK This palm-sized rock is from the beach at Eccles-on-Sea (North Sea coastline).

I can see four types of material:

A brown, slightly translucent, 6cm tubular fossil(?) that I can mark with a steel blade;
Coarse, light material--stained reddish-brown in places--that I can scratch away with a fingernail;
Hard, dimpled, dark-brown material that I can't scratch (iron perhaps?); and
Shiny black stone that I can't scratch.

I'm mostly interested in the fossil--if it is a fossil. Thank you. :-)

The round one is a belemnite... The grid-shaped fossil is a bryozoan. Bryozoans were (and are) marine colony building organisms often encrusting shells and other hardgrounds in the oceans. There are also solitary bryozoan colonies, which form screw-like shapes.

A nice picture of a bryozoan similar to yours can be seen here


How can a crystal habit be round? I am confused how hematite can have a "botryoidal" habit when its crystal structure is trigonal, which is an angled structure.

How can an angled crystal present itself as rounded?

If a botryoidal crystal of hematite is examined microscopically, is it clear that it is trigonal? How is that?

Botryoidal habit describes the arrangement of a large group of hematite crystals.

While hematite's trigonal crystal system describes the geometry of a single unit crystal of hematite,  the two terms are really not related at all. Many minerals with different crystal systems can have a botryoidal habit.

The difference between a Botryoidal habit and mineral's unit crystal geometry is a difference in scale. A botryoidal habit can be measured in inches to feet while crystal geometry is measured in Ångstroms.


Are Southern Hemisphere 'Polar Blasts' caused by global warming? The SMH journalist writes about a cold snap hitting the East Coast of Australia in July 2015:

Proof of the big chill will be the extent of regions across Tasmania, Victoria and NSW experiencing zero temperatures, the Bureau of Meteorology said.
A belt of low pressure systems is a fairly permanent feature of Antarctica. One of those lows - at a latitude of about 55-60 south - is currently to the south of Tasmania and further from the Antarctic coast than usual, Dr Trewin said.

What would cause this low pressure zone to extend further from the Coast of the Antarctic than usual? Could it be a large chunk of ice melting?
My question is: Are Southern Hemisphere 'Polar Blasts' caused by global warming?

Looking at the southern hemisphere polar jet, there is a large trough (meander) in the jet stream bringing cold air a long way north from the Antarctic to south eastern Australia at present. The relevance of the position and shape of the jet stream is thought to be important for keeping cold polar air in place above the antarctic/arctic, with a strong jet stream keeping cold air hemmed in above the poles while a weak jet stream meanders allowing cold waves/blasts to escape into the midlatitudes. This previous Stack Exchange question sets out how the theory of arctic/polar amplification which is thought to affect the position and shape of the jet stream is being studied in connection to climate change (Generally it has been proposed that global warming will make the jet stream more wobbly/meandering, and so increase instances of cold weather in the mid latitudes).

Single weather events such as this are not caused by global warming, but it has been hypothesised that their frequency of occurrence may change due to warming, though as you can read in the linked stack exchange this theory is not universally accepted.


How to perform precipitation data analysis? I want to make precipitation data analysis for the Latvian territory.
I only have meteorological stations and reanalysis  data.
My data from meteorological stations are in the format:

year  month  day    time      station1 station2 station3
2013    1     1    03.00        0                 0.1
2013    1     1    06.00        0.1               0.2
2013    1     1    15.00        0       0.1         0
2013    1     1    18.00        0.2     0         0.3
2013    1     2     03.00        0                 0.4
                  ...

I also have a file with coordinates for meteorological stations.
And data from reanalysis is in format

> head(data)
  longitude latitude   time value
1     -27.0      -27 990555     0
2     -25.5      -27 990555     0
3     -24.0      -27 990555     0
4     -22.5      -27 990555     0
5     -21.0      -27 990555     0
6     -19.5      -27 990555     0

Edited: My main questions are:
1) What can tell me if these data are similar, should I look their summary and compare, or it is better to use some tests. Could you advice methods how to compare different data.
2) If there are missing values, should I just get them out and then analyse data?
3) Maybe someone can advice some tutorial with R code? Can someone tell me how to decode time values from format like 990555 (I need formula or function for R)?

Date/timestamps are tricky to convert without further information; are the values you show days (unlikely, if 990555 is your date/time value), hours, seconds? See if you can figure out the system used (either by knowing which date your timestamp is supposed to represent, or looking at the step sizes for the data); this will generally give you an idea of what is being represented, and how to convert to an actual date.
Coordinate and long/lat are basically the same thing, only built up from decimals or hours/minutes (e.g. 0.5 representing 30 minutes). Conversion can be found http://transition.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html, for instance. Mind that other coordinate systems are also possible, which will make the conversion different; again, this is important to figure out before you can convert your data.
Comparison options will depend on: 1) whether your data corresponds (do you have measurements on the same date/time, as well as the same location?), 2) what you are interested in.


Can miniature shells be seen in Earth's sand at this resolution? Most of sand on Earth when inspected at close range reveal tiny shells as in sea shells.

Here is a picture of the Martian sand at a close distance:

Can Earth's tiny shells be seen in sand at similar distance?

Firstly I would disagree with your premise that 'most of Earth's sand contains tiny shells resembling sea shells'. Such biogenic sand is certainly true of some biologically productive sedimentary environments, but certainly far from all. For example, try finding shells in most of the sand in the Sahara desert, or any other desert for that matter. You will only succeed if the sand is reworked from previous biogenic sandstone.

As to the resolution of shells at the apparent scale of your photograph, it depends upon the biota involved. The bioclasts vary from several millimetres to true microfossils - far below any visible resolution, and maybe even below resolution of small microscopes.

I assume that any close up photo of Mars sand would have been magnified, contrast stretched, and computer image enhanced. Had there been any bioclastic grains, I am sure it would have been front page news around the world.


Will we even be burning fossil fuels in approx. 100 years? Worry about climate effects? Do we really need to worry about the effects of burning fossil fuels when in all likelihood we won’t be burning fossil fuels in about a 100 years or maybe a little more?

We will have technologies in about 100 years where burning fossil fuels will seem like using a steam engine today. I think it will be laughable / primitive to burn fossil fuels.

It will be rare to burn fossil fuels for power and not of consequence to the environment any longer.

What are we really worried about when we are just going to be burning them for a little bit longer?

Can we really do that much damage over the next hundred years if we are somewhat reasonable?

Based on the stats for the US only, I would say we have the capacity for using fossil fuels over the next 100 years.  Whether or not we worry about it is another discussion entirely.  The US has coal resources for the next 250 years and I suspect may be producing and using natural gas for the next 100 years.

For the US (from the US Energy Information Administration)

256 years of coal resources available (based on 2014 numbers) link
~12 years of natural gas resources available
Based on resources and current usage rate Link

This is a rough estimate does not take into account importing or exporting natural gas.Also assumes usage based on 2015 numbers.
0 years of oil resources (no surprises here)
US uses 19.4 millions of barrels per day link
US produces <9 millions of barrels per day link

Here is fun stat laden site for global oil and gas resource and consumption. link.

Note: I take these stats at face value but oil resource production and reserve numbers are not always accurate.  A number of oil producers are reluctant to provide accurate stats as these numbers are considered sensitive to their economies.


How much of the petroleum ever formed has made it into reservoir rocks? I am aware that it's a bit general a question, and petroleum geology (or petrology ;-)) has never been a field of interest to me. A superficial search using related keywords brings up only economic figures about percentages here and there.
From a geoscience point-of-view is there any chance to give an estimate, however rough it may be, of how much was ever produced in the biospehere (and abiogenic if that plays a role and can be set in number), and how much of that made it into reservoirs ?
I am very well aware that there is a lot of uncertainty, concerning formation processes, mobility in the crust, amount of current storage, past conditions favourable for the formation, etc, but maybe petroleum geology has once thought about it, and knows a rough number.

In its 1995 assessment of total world oil supplies, the U.S. Geological Survey (USGS) estimated that about 3 trillion barrels of recoverable oil originally existed on Earth and that about 710 billion barrels of that amount had been consumed by 1995.
Britannica

There may be much larger quantities that are not "recoverable", depending on technology and economics.
Also, for example, 914 persistent natural seeps across the Gulf of Mexico collectively discharged about 500,000 barrels of oil per year. If that has been seeping for millions of years, that is a lot of oil that is not in reservoirs.