Is the Mauna Loa CO$_\mathsf{2}$ record affected by the nearby mantle plume? How is it possible that Mauna Loa Observatory is the International Reference Observatory for CO2 Global Measurements if it is placed above the most important earth thermal plume that is heating the ocean all the year? How reliable can these data be? Is it due to the 3000 m altitude of the Observatory? Does not affect the geological Hawaiian situation?

How is ist possible that Mauna Loa Observatory is the International Reference Observatory for CO2 Global Meassurments

I don’t know that it is ‘the International Reference Observatory’. The Mauna Loa record is almost certainly the most-cited decadal-scale CO2 record, but as far as I know the observatory hasn't been accorded any special status: the record is used on its own merits. Googling for the phrase ‘International Reference Observatory’ gave me precisely one hit, which strongly suggests that it's not a well-defined term. The hit comes from Roussel-Debet et al. (2006), and appears in the following context:

  … the atmospheric CO2 values measured at the international reference observatory at Mauna Loa (Fig. 5)…

Note the lack of capitalization. I don’t think that this implies the existence of a single, officially defined ‘International Reference Observatory’ at Mauna Loa. Rather, it's like writing ‘the solar observatory at Mauna Loa’: there are many solar observatories, and this clarifies which one we're talking about. Similarly, there are several observatories which produce internationally used CO2 data, and this specifies which one we’re talking about here.

  if it is placed above the most important earth thermal plume that is heating the ocean all the year?

It’s true that there is a posited mantle plume below Hawaii, so it seems likely that there might be increased thermal heat flux at the sea-floor. (Incidentally, I’m not sure what would make this mantle plume ‘the most important’, or even how one would quantify the importance of a mantle plume.) However, Von Herzen et al. (1989) found that

  … even though there is a small increase in heat flow with age along the swell, when compared with the off-swell heat flux, the anomalous heat flow associated with the Hawaiian Swell is probably of the order of 5–10 mW m−2 and arguably may not exist at all.

But more to the point: even if there is slightly increased heat flux here, why do you think it would affect the CO2 readings? What mechanism are you suggesting by which a small amount of conducted heat, several kilometres below sea level, is able to perturb atmospheric CO2 concentrations several kilometres above sea level?

Finally: even if there were such a mechanism, the mantle plume operates, as you point out, ‘all the year’ – year in, year out, for millenia before the Mauna Loa station even existed. So at worst it would produce a constant offset, and wouldn't affect the trend of the measured CO2 concentrations.

  How reliable can these data be?

Very reliable indeed! Look at this comparison with records from Samoa, Barrow, and the South Pole.

Source: NOAA

Naturally, the shape of the annual cycle varies depending on the measuring station's latitude (you can see that the South Pole record is out of phase with the northern hemisphere records, as you'd expect), but the trends are an indisputably excellent match. If there were some confounding local influence at Mauna Loa, we certainly wouldn't see it reproduced at other sites thousands of kilometres away.

  Is it due to the 3000 m altitude of the Observatory?

That's certainly one factor that makes Mauna Loa an excellent site for this kind of study. This Skeptical Science page lists some others:

  Early attempts to measure CO2 in the USA and Scandinavia found that the readings varied a lot due to the influence of growing plants and the exhaust from motors. Mauna Loa is ideal because it is so remote from big population centres. Also, on tropical islands at night, the prevailing winds blow from the land out to sea, which effect brings clean, well-mixed Central Pacific air from high in the atmosphere to the observatory. This removes any interference coming from the vegetation lower down on the island.

For more detail on how measurements are taken at Mauna Loa, and how the data is checked to make sure that it’s not contaminated by local influences, see this detailed NOAA page on measurement procedures. The section on ‘Data selection for background air’ is particularly relevant to your question. (Thanks to jeffronicus for providing this link in the comments.)

As to your final question:

  Does not affect the geological Hawaiian situation?

I assume that you meant to write ‘Does the Hawaiian geological situation not affect the readings?’. I hope I’ve made it clear that it doesn’t, and that Mauna Loa is so widely used precisely because of the absence of local influences on the readings.

References

Sylvie Roussel-Debet, Gilles Gontier, Françoise Siclet, Marc Fournier, Distribution of carbon 14 in the terrestrial environment close to French nuclear power plants, Journal of Environmental Radioactivity, Volume 87, Issue 3, 2006, Pages 246–259, ISSN 0265-931X, doi:10.1016/j.jenvrad.2005.12.002.

Von Herzen, R. P., M. J. Cordery, R. S. Detrick, and C. Fang (1989), Heat flow and the thermal origin of hot spot swells: The Hawaiian Swell revisited, Journal of Geophysical Research, 94(B10), 13783–13799, doi:10.1029/JB094iB10p13783.


What is radiation divergence? What is radiation divergence, in the context of atmospheric physics? For example, the phrase is used in this paper.

The way I understand it, the net longwave radiation $L^\star:=L^\downarrow-L^\uparrow$ (maybe with different sign), i.e. the difference between downwelling and upwelling radiation, can be viewed as a vector field (with vanishing horizontal components under the assumption of homogeneous horizontal radiation distribution). This vector field has a divergence $\nabla\cdot L^\star=\frac{\partial L^\star}{\partial z}$.

This term occurs in equation (1) of the paper you referenced as part of the heating rate. Since non-vanishing divergence is in a vector field is associated with the field having a source or sink, this corresponds to heating/cooling of the atmosphere.


Is there any river that does not discharge into larger body of water? Do you know any example of a river that does not flow into sea or lake? For example, if water rises from the underground spring and forms a river but water vaporises in hot climate before it reaches any larger body of water. Or if there is a valley with very moderate precipitation and many little creeks flow out of the valley and the water from them is absorbed by the soil.

The Okavango River is a good example of this. It drains into a swampy delta in the middle of the Kalahari desert:

The Okavango Delta, CC BY Justin Hall.


What causes the counter-intuitive presence of CO2 in the atmosphere during spring and summer months? Recently, I stumbled upon this NASA map of the Earth from the OCO-2, a satellite that measures CO2 density in the atmosphere. http://www.climatecentral.org/news/nasa-tools-co2-19681 Specifically, I'm refering to the tool with the CO2 heat map with the split-screen slider.

As you can see during the spring, there is less CO2 over open ocean and higher CO2 over landmasses. During the summer, (by the naked eye) there seems to be a higher CO2 density across the path the satellite took. I'm curious the reason for the differences we see.

I would expect that during the summer months, when there is a higher density of CO2 , that there would be a lower density of CO2 because of an overall increase in vegetation. During the spring, there would be more CO2 because of a significant decrease in vegetation and increase in energy consumption in the Northern Hemisphere (but not as much as during heavy winter).

Am I making a wrong assumption? What am I missing?

I think this is a distinct question from this one because I'm asking only in the scope of one year or across consecutive seasons.

From Scripps:

  [The] latitudinal differences in fluctuation are the result of photosynthetic activity by plants. As plants begin to photosynthesize in the spring and summer, they consume CO2 from the atmosphere and eventually use it as a carbon source for growth and reproduction. This causes the decrease in CO2 levels that begins every year in May. Once winter arrives, plants save energy by decreasing photosynthesis. Without photosynthesis, the dominant process is the exhalation of CO2 by the total ecosystem, including bacteria, plants, and animals.  Two regions of Earth contain the majority of land plants: Northern Hemisphere continents and the tropics that encompass ... the vast rain forests of the Amazon basin. Near the equator, however, the seasonal variations in temperature are less pronounced. Seasonal swings in CO2 are therefore most pronounced in the Northern Hemisphere, where the seasonal changes in temperature result in very large differences in plant photosynthesis from summer to winter.

My interpretation of the slide-graphic confirms the idea that more CO2 exists earlier in the springtime, especially in the Northern Hemisphere.  There are darker reds (~403 ppb) over most of the northern latitudes in March/April

and more of an orange-yellow color in June (~400 ppb).

In general, I would caution you in putting too much meaning into graphics that NASA develops such as these.  These graphics are made by concatenating a couple weeks of satellite overpass data (generally one to two retrievals per pixel).  These are not an "average" like you might think.  This is because the swath of the instrument detection is very thin, thus requiring weeks to get "global coverage".  Furthermore, the OCO CO2 algorithms are still being refined, and will go through several more revisions before the data is "finalized".


Is a controlled fractional crystallization process feasible on the Moon? I am looking for a way to separate metal oxides on the Moon. Please bear with me - it's for an ultra-hard science fiction project. Processes typical on Earth are not effective there. Heat is cheap on the Moon, there is strong constant sun that is easily concentrated. Heat also dissipates slowly thanks to the vacuum, and reflective insulation can be used to slow heat loss much more.

So, I wondered if a form of controlled fractional crystallization could be used to get pure olivine from a molten melt of rock, and then the olivine could be split into forsterite and fayalite the same way. The forsterite might make decent clear glass, or if not, the fayalite can be processed with hydrogen to get iron, water, and silica, and the silica can be used to make glass. It might be necessary to apply centrifugal force to get the crystals to separate in the Moon's low gravity. If the technique works, it would seem the same process could be used to isolate other metal oxides through other paths.

Hydrogen and carbon atoms are present on the level of around 100 ppm. Am I correct in thinking that mineral separation would occur this way and could be controlled to get good purity? I know there are engineering issues, but in terms of the geochemistry, is it correct that crystallization and settling would occur in this way?

(Note: I heavily edited this after my continued searching on the topic finally got me to 'fractional crystallization', and then I came across a few things that made me rethink the whole thing.)

First, read my highly related answers to your other questions:

https://chemistry.stackexchange.com/q/67403/8083

https://chemistry.stackexchange.com/q/72483/8083

  The forsterite might make decent clear glass

Probably not, see above.

  fayalite can be processed with hydrogen to get iron, water, and silica, and the silica can be used to make glass

Again, probably not. To make the fayalite component react fully in reasonable time you are going to need to mill the olivine to very fine dust. Then, separating the silica from this fine dust in solid form is almost impossible. This will require heavy liquids (like polytungstate) which are not available on the moon. Doing this in liquid form and centrifuging will require heating, which will inevitable cause reaction of forsterite and silica to form enstatite: $\ce{SiO2 + Mg2SiO4 = 2MgSiO3}$, which is useless for glass making.

  Is a controlled fractional crystallization process feasible on the Moon?

Basically yes. This would be similar to a distillation process that slowly over repeated melting and solidification processes will remove Mg-rich solid from Fe-rich liquid. The problem is that even very low amounts (1% and lower) of Fe in forsterite will colour it green, which is undesirable for your glass. And that's without even considering the forsterite is not a good glass material (see links above). Seperating the Mg out will become harder and harder as you go along in your process.

Good glass material has alkalis in it. Fortunately, some lunar rocks have Na and K in them (e.g. the KREEP basalts). It has about 1 % of potassium, which could be enriched in fractional crystallisation. The problem is that you will also enrich the glass in Th, making it slightly radioactive and possibly browning with time.


Are there plants or bacteria that perform NO2 fixation and how relevant are they for improving local/regional air quality? Nitrogen dioxide (NO2) is a relevant air pollutant i.e. by contributing to the ozone (O3) production.

I was wondering if there are any plats or bacteria that fix NO2. I have read that legumes fix N2, but I'm unsure about NO2.

Moreover, I was wondering whether this NO2 fixation - if existing - significantly reduced local or regional NO2 concentrations improving air quality.

Can anyone answer these questions?

Thanks

NO2 uptake by plants

It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [Breuninger et al, 2013]. Currently, it is assumed that NO2 is taken up through stomata of plant leaves when the atmospheric NO2 concentrations are above a certain threshold. However, when the atmospheric NO2 concentrations are below this threshold, plant leave stomata act as sources for NO2. Therefore, this process is not fixation in the sense as N2 is fixed by legumes.

See Breuninger et al. [2013] and refernces therein for details

Canpoy reduction

Plants do not only take up (excess) NO2 actively but they decrease the concentrations of several air pollutants by providing a lot of surface for dry deposition as Christoph stated in his comment. After deposition they may revolatilize or be washed down by rain. See e.g. Grundström and Pleijel [2014] for details.

Impact on air quality

The presence of plants/trees in urban environments can reduce ambient NO2 concentrations. However, this effect is not due to NO2 fixation but due to the canopy reduction/enhanced dry deposition rate, which also yields a reduction of other air pollutants. See e.g. Grundström and Pleijel [2014], Yang et al [2005], or Yang et al. [2008] for details.

The canopy reduction is also considered in recent regional modeling studies - see e.g. Arndt et al. [2016] (Disclaimer: I was member of that working group until recently). It can be seen like increasing the surface roughness.


Did a gamma ray burst contribute to the Ordovician mass extinction? According to the University of California Museum of Palaontology webpage The Ordovician Period, the late Ordovician period witnessed

  when Gondwana finally settled on the South Pole during the Upper Ordovician, massive glaciers formed, causing shallow seas to drain and sea levels to drop. This likely caused the mass extinctions that characterize the end of the Ordovician in which 60% of all marine invertebrate genera and 25% of all families went extinct.

NASA's webpage Explosions in Space May Have Initiated Ancient Extinction on Earth and the paper Did a gamma-ray burst initiate the late
Ordovician mass extinction?  suggest that a gamma ray burst may have initiated the cooling at approximately 440 million years ago.

What palaeoclimatological and geochemical evidence is there to support or refute the gamma ray burst cause of the late Ordovician mass extinction?

As a preamble, let me say that I don't know remotely enough on galactic dynamic to know if a supernova could have possibly been close enough during the Ordovician for Earth to be affected by a gamma ray burst, nor do I know enough about geochemistry to know if there are ways to detect such an event in the fossil record.

That being said, the questions that I'll try to answer are: do we need to invoke an extraterrestrial event to explain the Late Ordovician glaciation? does the taxa selectivity of the extinction event support the GRB hypothesis?

So let's look at the different hypotheses on how the glaciation occurred, the original conundrum being: how could a glaciation occur when mid-Ordovician $p_{CO_2}$ is believed to be up to 14 times Quaternary level? Brenchley et al. 1994 suggested that the Ordovician ocean circulation changed from a system having warm saline bottom waters to a system with cold bottom waters (i. e. a thermohaline instead of an haline circulation), which triggered a phytoplanktonic bloom, which then decreased atmospheric $p_{CO_2}$ and provoked an eutrophization of the ocean. Kump et al. 1999 argued in favor of a tectonically derived $p_{CO_2}$ decline: with the Appalachian and Caledonides orogenesis came an increased weathering which decreased $p_{CO_2}$. Of course the two hypotheses are not mutually exclusive since increased weathering also means increasing nutrients in seawater and therefore increasing primary productivity.

Another question is which groups went extinct during the glaciation: recent studies show that acritarchs (the most diverse group of phytoplankton known for that period) did not suffer from these events (Vecoli 2008); oppositely benthic group such as crinoids or brachiopods did (see Sheehan 2001 for a review); some pelagics groups such as graptolites and nautiloids did suffer as well during the event while some other didn't (radiolarians for instance). In summary there is no clear pattern, but there is also no reason to think that there was a preferential extinction of surface organisms over deeper-living ones.

So, does that answer the question: no; but it seems to me that GRB doesn't explain better the event that unfolded during the late Ordovician than other hypotheses (namely the ocean eutrophization and the continental weathering). Does it discard the hypothesis of a GRB: no; but since there is no direct evidence that it indeed happened at that time, and that we can explain the Ordovician events without, it seems, to me, more parsimonious to think that it didn't.

References:
Brenchley et al., 1994. Bathymetric and isotopic evidence for a short-lived Late Ordovician glaciation in a greenhouse period. Geology, 22: 292-298.
Kump et al., 1999. A weathering hypothesis for glaciation at high atmospheric $p_{CO_2}$ during the Late Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology, 152: 173-187.
Sheehan, 2001. The Late Ordovician Mass Extinction. Annual review of Earth and Planetary Science, 29: 331-364.
Vecoli, 2008. Fossil microphytoplankton dynamics across the Ordovician–Silurian boundary. Review of Paleobotany and Palynology, 148: 91-107.


Is there a conventional list of pollutants to consider for calculations? Or an updating one even? In researching economic damage from various pollutants, I often find that it's very random sources that inform me of various pollutants I need to be mindful of in calculations. Is there any kind of overarching list of known problematic pollutants that one needs to consider in calculations for environmental factors?
For instance, you might have pesticides, heavy metal aerosols, heavy metal colloids and solutions, fertilizer runoff, sewage, etc. But, how do I know there aren't more? There must be some kind of standard list, maybe the European Union or one of the environmental agencies in North America has a list of pollution categories that damage the environment.

In the USA there are two classifications of airborne pollutants. They are

Criteria Air Pollutants

There are 6 separate air pollutants. These make the bulk of the regulation, especially for the Clean Air Act. Each pollutant has different standards to adhere to. Examples include lead, ozone, and particulate matter.

Hazardous Air pollutants

This is a list of 187 pollutants. These are cancer-causing pollutants, but are usually in pretty low concentrations. Examples include asbestos, lead, and benzene.


How far a andesitic lava can flow and what is the speed? For an effusive volcanic activity how far a andesitic lava can flow?
What is the speed?

Eruption amout 0.2 cubic km amount with 25 degree slope.

Andesitic lava is viscous, compared to basaltic lava. Andesitic lava flows at a rate of a few kilometers per hour, whereas basaltic lava can flow up to 10 km/h. Because of their viscosity, andesitic lavas "rarely extend beyound 8 km from their vents".

Viscosity of andesite lava and its implications for possible drain-back processes in the 2011 eruption of the Shinmoedake volcano, Japan

Pulsatory andesite lava flow at Bagana Volcano

Volcanoes, Magma, and Volcanic Eruptions - Tulane University


Aren't fresh water deposits renewed by the water cycle? I have recently watched the documentary "How Many People Can Live on Planet Earth?" with David Attenborough. In it, the main factors that will limit total human population Earth can support are named. One of these was the limited amount of fresh water. There also was a part where it described how fresh water is distilled from astronaut urine on the International Space Station  .
My current understanding is that all the water (fresh or not) in nature (i.e. on planet Earth) is infinitely going through a water cycle, and thus non-fresh water is sort of distilled into fresh by this natural process.
My questions are:

Where am I wrong in my assumption about natural water distillation (i.e. is rain water not as clean as it should be in theory)?
Why don't we collect rain water (at least for plant watering, if it is not suitable for drinking)?
Theoretically, after an animal has consumed some amount of water, say a glass, how long will it take, after that animal urinates on the ground, for that water to go through the water cycle and become ready for drinking again?

Rain water is still one of the most cleanest water sources available. There may be some ancient underground aquifers that have clean uncontaminated water.

One issue with rain water is that atmospheric moisture - part of the water cycle - needs to condense on aerosols in the atmosphere before it can develop into rain. With the amount of pollution humans are dumping into the atmosphere some of that can form the aerosols that eventually develops into rain thus making rain water dirtier than it used to be - such as acid rain being formed when sulfur dioxides are dumped into the atmosphere when high sulfur coal is burned in power stations. Other aerosols include salt from the oceans.

The other issue with rain water is that the soil in water catchments can be contaminated by pollution. Rain falling on the catchments can absorb some of the contaminants thus making the rain water in the resultant catchment dirtier that it might have been in the past.

Regarding the rate of urine production of animals, it depends on the type of animal. A mouse will process water at a different rate to an elephant or domestic live stock. It is also influenced by circadian rhythms for each type of animal.


What (if anything) can be learned from accurately recording tilt motion during seismic events? The Rotational Motions in Seismology (ROMY) instrument is a giant laser gyroscope used to generate extremely precise 3D rotation measurements of planet Earth. However at the end of the video below they mention that "seismologists want to..." use small laser gyros to measure seismic tilt motion as part of earthquake monitoring.

Is there a lot of interest in this? Have compelling questions been identified that could be address by adding tilt motion to translational motion monitoring, or is it a case of nobody's looked, there might be something interesting there, better find out?

https://youtu.be/MXYV6wNdZm8?t=102

The intent with this (very, very cool) device seems to simply be to improve hazard assessment and mitigation by providing higher resolution motion data.

It reminds me of tiltmeters used on volcanoes. These devices measure changes in the flank slope of a volcano in order to assess volatility and risk (how the magma chamber is developing, etc.).

This kind of technology isn't new, but it's only been available in a precious few places. The ROMY will be able to cover a wide area, but the real holy grail is to have many mobile stations that can record local movements worldwide (as they mention in the video).


Why is a mild earthquake often mistaken as dizziness or vertigo? Is it due to the longitudinal nature of the seismic waves?

When a heavy bus or truck goes by at high-speed, the shaking in nearby ground is not mistaken as dizziness, rather the feet and body feel a vertical jerk (seemingly a transverse wave vertical to the ground).

But when a natural, mild earthquake takes place, it is not felt as a jerk or switch in a direction at all. Rather we feel it for a while as dizziness. I have experienced this, and heard of many others who have as well.  In-fact it takes a few seconds to distinguish whether it is dizziness or an earthquake.

Is it due to the longitudinal waves? Is it because they are horizontal with the ground, matching the direction of dizziness?

Also I guess maybe there may be similarity between the frequency of seismic waves and this video from Wikipedia's article on vertigo:

Does this phenomenon's frequency act similarly to the motion and simulates  dizziness?

Having experienced many minor earthquakes (Mag 3 to 5 in the East African Rift Valley, Samoa, Solomon Islands, Philippines and Indonesia), and one major life-threatening earthquake (Magnitude 8, Nepal), I can make a few personal observations about physiological reactions.
First, You are quite correct about the body picking up any swaying feeling, and interpreting this as dizziness. I was in an 11th floor hotel room in Bangkok when an aftershock of the Aceh earthquake occurred. My first thought was "Did I drink too much beer this evening"? I wasn't alone. When I opened the door into the corridor, the occupants of nearly every room were looking out and wondering much the same thing.

Second, after experiencing a big one the body becomes hypersensitive - conditioned to pick up vibrations that could be the onset of a major quake. Now, at the onset of any vibration, my brain goes straight to "how big is it - should I run to the nearest exit"? This response is now much faster than the sensation of dizziness. Also I now pick up many vibrations that nobody else around me seems to notice.

Thirdly, I am not sure I agree with you about vertical motion being the trigger. It seems to me that lateral motion - moving one's feet sideways relative to the head, creates a slight imbalance, which the ears interpret as 'dizziness'.


Judging wind speed based on flags and inland-water observations About a year ago, I took this video along the Hudson river in NY, and I'm trying to figure out the Beaufort number based on the water and the flags.

https://www.youtube.com/watch?v=nqjvTALRWW8

The problem is that the Beaufort scale is based primarily on open sea waters (not protected/inland waters like the Hudson river).  The only mention in the scale relating to inland waters is force 5 ("crested wavelets (whitecaps) form on inland waters") - but nothing related to the higher force numbers.

In this video, there are definitely lots of whitecaps, which leads me to believe that the wind was force 5 or higher.  Possibly even a 6.

Flags are another indicator; but here it is kind of vague.  At force 5, flags start rippling and flapping hard, and as the wind gets stronger, they start beating/snapping, until finally they are fully extended with only the very end flapping (force 7).  So looking at the flag in the video makes me think it's a 6.

What steady force/speed is the wind really blowing here?  What about gusts?

I would call that about a force 3. But be aware that one of the problems near shore is that the shoreline, buildings, and topography have a large effect on the local winds - both direction and speed. Also fetch makes a difference - waves don't have enough time/space to build to their full size without sufficient fetch. Not the case in your video but it is difficult to evaluate waves when looking downwind because you see the less-steep backs of the waves and maybe only the tips of the whitecaps.

Sea kayakers have some decent resources for estimating winds near-shore because most kayakers spend the majority of their time in that environment. Here is one example.


Formation of petrified trees In my book, I came across this question:

  Give reason why formation of petrified tress is considered as a degradation and a sedimentation action of the underground water.

My book explains that underground water replaces the original plant material in trees with silica and other inorganic materials, and states this as a sedimentation action of underground water. But I don't understand the part of "degradation action" in the question, I think underground water only replaces the plant material in trees so why we consider this to be a degradation action? Or the degradation action mentioned in the question is something else? And if yes, could you explain it for me? Thanks in advance!

But I don't understand the part of "degradation action" in the question, I think underground water only replaces the plant material in trees...

Degradation refers to the process of aqueous dissolution of the organic materials; the fact is, organic materials are generally quickly dissolved after the death of a living organism...degraded into nothing before the fossilization process can even start. (Think of the carbon cycle and how organic compounds are re-used over and over again over the eons of life on this planet.)

It's a bit of a misnomer in this case because it ignores the simultaneous replacement of that organic matter with inorganic siliceous materials.


Deciphering NCDC data I need US monthly climate data for the years 1992-2012. It would be great to get down to a county level, but by state would be just fine. Every site that I go to inevitably kicks me to the NCDC, but I cannot make sense of their data.

For example: the .csv sample data for  GHCN Monthly Summaries  lists EMXT (extreme maximum temperature) for each month of 2010 in Petersburg, ND. July had an EMXT of 317. I've been through the documentation, but I can't figure out what that number is supposed to mean. I know it wasn't 317F or C in ND at any point. Did they add all the temps up? Was it around 10C every day of July 2010? But why would you do that? The .PDF data looks like actual temperatures, but I need a lot of data: .CSV is ideal; .PDF is really not useable for the amount of data I am going to manipulate.

What am I missing? Or is there another way to get this data?

The documentation linked from the datasets page states:

  Air Temperature (all units in Fahrenheit on PDF monthly form and tenths of degrees Celsius on CSV or text)
  EMNT - Extreme minimum temperature *
  EMXT - Extreme maximum temperature *

The Petersburg data looks plausible under this interpretation (EMXT −3.9°C to 33.9°C over the year).


How much silicon is in the Earth's core, and how did it get there? With some informal conversation with a peer of mine, he had suggested that there is evidence (which he couldn't find,but had remembered reading) that there was Silicon in the Earth's core. I referred to him to a rather famous paper by Micheal Drake which says:

  "Further, there is no compelling experimental evidence that Si is extracted into the core under present core-mantle boundary conditions. For example, at the base of a high pressure/temperature terrestrial magma ocean, the metal/silicate partition coefficent for Si is approximately $10^{-3}$ to  $10^{-2}$"

But since this paper was published 12 years ago, I am wondering if there is any compelling evidence that Si is in Earth's core, and at what concentration it might be? How might it have gotten there?

References

Drake, M., Righter, K., 2002. Determining the composition of the Earth. Nature 416, 39–44.

The only way presently is to simulate the conditions in the core, as has been performed in the article Oxygen and silicon contents of Earth's core from high pressure metal–silicate
partitioning experiments (Ricolleau et al. 2011), whose results indicate that

that the oxygen metal–silicate partition coefficient increases
with increasing oxygen fugacity, temperature and pressure, whereas the silicon metal-silicate partition coefficient increases with decreasing oxygen fugacity, increasing temperature and pressure.

The model also revealing that the approximate concentration of silicon in the core (outer core) is up to 11 wt%, depending on what model of core formation was used in the simulation.  These results

in the core could satisfies the seismologically observed range of outer core
density deficits.

In terms of how long the silicon is believed to have been in the core, in the article Silicon in the Earth’s core (Georg et al. 2007), similarities with the silicon content with the Moon led to their conclusion that

$Si$ was already incorporated as a light element in the Earth’s core before the Moon formed.


On what basis are hurricanes,cyclones or typhoons named? now its well known that common names are used to name weather storms but on what bases are they named ? is it the person who first notices them ? Is it the the most common name in the region where the cyclone/typhoons/hurricanes develop ?or something else entirely ?

The names are set well in advance. For example, the first four north Atlantic hurricanes in 2022 will be named Alex, Bonnie, Colin, and Danielle. In fact, the names of the north Atlantic hurricane in 2022 will be exactly the same as those in 2016, with one exception. Hurricane Matthew in 2016 was a catastrophic category 5 storm that claimed a number of lives and that resulted in large economic losses. The name Matthew has been retired because of this, so the 13th named north Atlantic storm in 2022 will be named Martin rather than Matthew.  The US recycles the names it uses on a six year basis, but the names of significant storms are retired and replaced with some new name.

Names for tropical cyclones elsewhere in the world follow a similar convention. Names are set well in advance, with the lists of names being recycled after some number of years. As was the case with Matthew, the names of catastrophic storms that result in a number of deaths and/or large economic impacts are retired from those lists.


Question Concerning Meteorite Ejecta Travel I was researching more into the studies done by Kjaer and his team ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235527/ ) concerning the hypothesis about the Younger Dryas impact crater named Hiawatha in Greenland and its dating. Another study by Pino et al. ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416299/ ) proposes that some of the Younger Dryas Boundary located in Chile could potentially be associated with the impact of Hiawatha and travel of impact ejecta.
Regardless of the pending measurements of the exact age of the meteoric rock located under the Ice Sheet to confirm age, my question is this: did the ejecta travel through the atmospheric circulation, which I find to be a possibility due to the polar vortex air currents carrying it over the North Pole, or was it simply from the explosive force which the meteorite was theorized to fall with? I know that with eruptions like St. Helens volcanic ash can circulate far and wide through the atmosphere, but with the amount found in Chile would this more line up with a blanketing of ejecta or just trace amounts finding its way there?
Kjær KH, Larsen NK, Binder T, Bjørk AA, Eisen O, Fahnestock MA, Funder S, Garde AA, Haack H, Helm V, Houmark-Nielsen M, Kjeldsen KK, Khan SA, Machguth H, McDonald I, Morlighem M, Mouginot J, Paden JD, Waight TE, Weikusat C, Willerslev E, MacGregor JA. (2018). A large impact crater beneath Hiawatha Glacier in northwest Greenland. Sci Adv. 2018 Nov 14;4(11):eaar8173. doi: 10.1126/sciadv.aar8173.
Pino, M., Abarzúa, A. M., Astorga, G., Martel-Cea, A., Cossio-Montecinos, N., Navarro, R. X., Lira, M. P., Labarca, R., LeCompte, M. A., Adedeji, V., Moore, C. R., Bunch, T. E., Mooney, C., Wolbach, W. S., West, A., & Kennett, J. P. (2019). Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka. Scientific reports, 9(1), 4413. https://doi.org/10.1038/s41598-018-38089-y

The research doesn't provide enough information to specify the displacement process of a 0.1mm spherule over 12,000 kilometers from North Greenland to Chile.
If the suggested impact was from Greenland, the space rock would have hit 800 to 1200 meters of ice at perhaps 10km/s which is the average for that kind of event.
Mount St Helens was about 0.25 km3 of ejecta, and the Greenland impact was a lot higher, i.e. 20km3 of vaporized rock.
Volcanoes send the energy out over many hours, whereas a YD meteorite would convert the energy relatively fast, perhaps mostly in the first 2 seconds. The thermal energy would have been very high, and the ejecta would have reached every level of the stratosphere, and the earthquakes would have emptied some lakes out in North America and left some major destruction fields in North America.
The same atmospheric displacement effects for all kinds of recent volcanoes would have been out measured considerably by a YT event.
Perhaps further studies will change the impactor site from the Greenland one which is perhaps 200k years old, to one in the Southern Hemisphere. At the moment, the evidence is so fleeting that the Nature article you gave has only generated a few lines of text on Wiki.


Why during subsidence inversion, upper layer warms more than lower layer? Source : weather.gov

This is mentioned in the book I have been reading regarding stability in atmosphere.
But I am not able to pin point exact reason behind this.

  "As the layer subsides, it becomes compressed by the weight of the
  atmosphere and shrinks vertically. The upper part of the layer sinks
  farther, and, hence, warms more than the bottom part." (Ahrens et al.,2019)

-Ahrens, C.D., Henson, R. (2019). "Meteorology Today: An Introduction to Weather, Climate, and the Environment". 12th Edition. Chapter 6 ( Stability and Cloud Development), CENGAGE Learning Custom Publishing, page 146-147

I assume that the sentence in the book mainly refers to subsidence as an adiabatic process. This sinking motion has a maximum which is at a height well above the surface, simply for the reason that air flow can not penetrate the earth's surface. Therefore maximum adiabatic heating rates occur well above the surface as well. The precise height where this occurs depends on the height of the planetary boundary layer, which itself depends on many more both adiabatic and diabatic effects.


What are today's methods in calculating the Local Magnitude of earthquakes? I'm no expert and barely have any idea about this. But I want to know if the methods in calculating the Local Magnitude can only be done manually? I mean manually by first reading a seismograph, identifying the distance of the epicenter using the distance between P-S waves, and then measuring the height of the highest amplitude. Or are there software, APIs, and etc that can do this automatically by just providing the seismograph data. Or there's no way to calculate the Local Magnitude without a human input?

According to the equation for local magnitude calculation I give my answer: Of course there is a lot of algorithms for auto-picking, in fact, the magnitude value that you see in the first report (immediately) after an earthquake is (almost always) an automatic calculation. https://academic.oup.com/gji/article/199/1/368/731808. However, the P and S picked time is checked but humans in order to improve the accuracy. I think the human verification is always necessary and obligatory, because some earthquake are complex signals. !. Moreover, the point here is not the human-based method, I thing it should be focused on the quality control system.


Can we determine strike when dip is given? What about the reverse? In any geological plane, strike gives the direction of a line formed by intersection of horizontal plane and geological plane. And dip shows the orientation of the geological plane. While studying, I came to know that strike is perpendicular to dip. But when I tried to determine dip from strike, I can not do it. But when I can determine strike when dip is known. So how can we determine dip if strike is known?

No. Strike is a line value whose direction is referenced with respect to true north. Dip can be any 0-90 degree angle (below horizontal) perpendicular to that line. It must be physically measured in the field....usually by some seriously underpaid graduate lackey.


Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.

What forces would cause such a mass movement of air?

Wind is caused by pressure differences.  Think of a balloon full of air; poke a hole in it and the air comes out.  Why?  Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.

There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role.  The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:

$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u  -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$

In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.

The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel).  The RHS represent a number of factors that produce a change in the wind.  From left to right:

Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)

For large scale synoptic flow above the surface, this is often simplified as a balanced flow called geostrophic balance.  This a steady flow with a balance between the PGF and Coriolis force in the horizontal and hydrostatic balance in the vertical.

$$ \dfrac{1}{\rho}\nabla p = 2 \mathbf \Omega \times \mathbf u $$

Which can also be written as

$$u_g = -\dfrac{1}{\rho f}\dfrac{\partial p}{\partial y}$$
$$v_g =  \dfrac{1}{\rho f}\dfrac{\partial p}{\partial x}$$
$$\dfrac{\partial p}{\partial z} = -\rho g$$

In these equations, $u_g$ is the geostrophic wind in the east/west direction and $v_g$ is the geostrophic wind in the north/south direction and $f$ is the Coriolis parameter ($f = 2\Omega\sin\phi$, where $\phi$ is lattitude).

For this idealized geostrophic and hydrostatic balance, there is no vertical motion and all horizontal flow is parallel to isobars, flowing clockwise (counter-clockwise) around high pressure in the NH (SH) and flowing counter-clockwise (clockwise) around low pressure in the NH (SH).

For curved flow, we can consider another balance, the gradient wind balance that allows acceleration of the flow though centrifugal forces.  This can be written as (where $n$ is in the cross-wind direction):

$$ \dfrac{V^2}{R_t} = -fV - \dfrac{1}{\rho}\dfrac{\partial p}{\partial n} $$

Where $R_t$ is the radius of curvature in the flow. In the limit of $R_t \rightarrow \infty$ the acceleration term vanishes and this becomes geostrophic flow.  The consequence of this balance is that wind will flow slower than geostrophic balance around a low pressure center, this is said to be subgeostrophic.  Around a high pressure center we have supergeostrophic flow, or faster than geostrophic.

You may have noticed the wind balances above are non-divergent and lack vertical flow.  This makes for boring weather, and does not hold near the ground or where vertical motion is large.

We term the deviation from geostrophic flow the ageostrophic wind and this accounts for friction.  This results in wind converging toward low pressure and diverging from high pressure.

Another flow is the isallobaric wind, and this is wind that blows from pressure rises toward pressure falls.  A place you will normally see this wind is just as a cold front passes and the pressure rises behind the front and falls in front of it.  This enhances the cross frontal wind and helps produce the often strong, gusty winds after a cold front passes.


How does the Sun heat the Earth? The core of the sun has a temperature of 15,000,000 °C.
The surface of the sun has temperature around 5,000 °C.
The sun is around 93 million miles (150 million km) away from earth.

My Question: With a surface of 5,000 °C, how does the sun provide heat for earth 93 million miles (150 million km) away?

It is a question of radiation emission - the temperature of the Sun's 'surface' is about 5500°C (according to NASA Earth Observatory), at that temperature, it emits radiation in the UV, visible and near infra red region - due to the fact that the hotter an object is, the smaller the wavelength radiation is emitted, as can be seen in the generalised image below (from NASA):

Note: the temperature of the Earth shown is an approximattion of its blackbody temperature, explained in the answer to the question What would be the temperature of earth if there was no atmosphere?.

Realistically,

Source: Wikipedia

Not all of this radiation reaches the top of Earth's atmosphere reaches the surface, a proportion is reflected off the atmosphere and some is absorbed by the atmosphere (as shown as the difference between the yellow and red in the diagram above) - but a good proportion reaches the Earth's surface.

But that is not the entire picture, we receive this 'shortwave' radiation from the Sun:

Which is also balanced by an equal amount of energy radiating into space as 'longwave' thermal infrared radiation:

(Both images from NASA Earth Observatory)

Which leads to a major point - we have an atmosphere and a natural 'greenhouse effect' due to the water vapour and carbon dioxide (and other components) that are seen in the above solar radiation spectrum diagram.

Some of the thermal infrared is absorbed by the atmosphere and re-radiated back to the surface. This radiation budget is shown below:

Source: NASA

Something to consider, looking at the value the NASA has for the incoming radiation reaching the Earth's surface - 168 Wm-2 - imagine that being a 168 watt light globes for every square metre - that value increases markedly when the re-radiated thermal infrared is taken into account.

Also, please view the YouTube clip How the Sun Heats the Earth which is a handy verbal and diagrammatic explanation of the content of this answer.


What formations are to be expected to develop between the transform boundaries of oceanic and continental plates? This could be needed in the Worldbuilding stack exchange instead of here, but when I was mapping out the movements of the tectonic plates, then there's a few locations where oceanic and continental plates are moving parallel to one another in opposite directions, creating transform boundaries.

I can't find anything regarding the formations that would arise from this, though I expect that something along the lines of cliffs might form, though this is pure speculation. What formations should I expect?

And as a side-note, I also found many cases of when one plate is moving parallel to the boundary, but the other plate is moving either convergent or divergent of that boundary. What formations should I expect from these as well?

The San Andreas Fault system is an excellent example of what can happen in an oceanic–continental transform fault.

It's also important to remember that plate boundaries are usually never 100% transform-like and are at an angle. This would cause either compression or extension, depending on the local geometry. A pull apart basin is an example of something like this. For instance, the dead sea is a basin on a transform fault between Israel and Jordan, and a few hundreds kilometres to the north, on the same transform, you have mountains between Lebanon and Syria.


Do we know anything about the nature of Earth's core that hasn't come from magnetic or seismic measurements? There is much known about Earth's core from painstaking analysis of seismic data, and from detailed magnetic field maps and trends over time.

Are there any other measurements that have contributed to current understanding of Earth's core besides these two?

Short answer: yes, most of our knowledge is not from seismics and geomagnetism, but from experiment and measurements, deductions from geochemistry and -physics, material science and physics in general (besides the already mentioned measurements of earth's gravity, but the variations are rather connected to mantle convection, water storage, etc. than the core). But all in all those weigh much more than "painstaking" seismics and geomagnetism.

One experiment to replicate pressure/temperature (p/t) conditions is the diamond anvil cell and its cascaded version in combination with laser heating of the probe, to obtain data about mineral and cristalline phases and transitions under conditions in a planet's core.

Wikipedia: Diamond Anvil Cell
Teaching Mineralogy; Topical Resources The Diamond Anvil Cell (DAC)

And some random links on the outcome of the matter:

Reviews of Geophyics: High-Pressure Experiments and the Phase Diagram of Lower Mantle and Core Materials
Nature Communications: Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar
Earth and Planetary Science Letters: The Earth's core composition from high pressure density measurements of liquid iron alloys
Geophysical Research Letters: Iron-Nickel alloy in the Earth's core

Laser pulses is a developing technique to reach very high p/t conditions, higher than diamond anvil cells can, but they do not last that long

Science Advances: Crystal structure and equation of state of Fe-Si alloys at super-Earth core conditions


How to estimate the runoff time for my area? I want to use an rainfall-runoff model for pluvial flash floods and need to choose for my synthetic rain event the appropriate duration. In the literature it often says that the chosen duration should be as long or twice as long as the runoff time from the beginning of the runoff until out of the catchment.

How do I estimate the runoff time? Perhaps somehow by considering the catchment area or the topography?

The suggestion above to check historical data to get an idea of the time to peak/ time of concentration, and a get sense of the general storm response time is a good one. There are also empirical methods to relate the catchment slope, runoff coefficient, etc. to the time to peak/ time of concentration, which sounds like what you are looking for. You can find examples of them in the MTO Computational Methods webpage, more localized ones might exist wherever you are located. Look for the section on time to peak, although you may need other definitions in there to determine your inputs to that calculation (such as catchment slope).
Keep in mind that 'runoff time' is not a specific term, and that the 'runoff time' for a full response may be extremely long, as nature tends to follow exponential responses trends with long tails in recession. However, the time to peak and time of concentration are more specific terms with definitions you can find and apply.
In terms of how long to run the simulation, depends again based on what you are doing. For a real storm, there may be subsequest rainfall events before the full response is seen. If you just need the peak, then 2-3x the estimated time to peak from the methods above would likely be fine, depending on how flashy the catchment is. If you are running a hydrologic model of sorts, then run it for a long time to see the full response to check the response hydrograph, and compare that to real data to help validate your model.


comparing use of Laplace equation with diffusion equation to simulate flow of fluid/water through porous media? What is the difference in using Laplace equation (say only in 1D) to simulate water flow in a porous media with that of using diffusion equation for same purpose?

The Laplace equation, (d^2 Ψ)/(dx^2 )+(d^2 Ψ)/(dy^2 )+(d^2 Ψ)/(dz^2 )=0, is just a steady state 3D flow equation. It's a black box conservation of hydraulic potential. Diffusion doesn't come into it. The Diffusion equation (assuming homogeneous isotropic conditions) is (∂^2 Ψ)/(∂x^2)+(∂^2Ψ)/(∂y^2)+(∂^2 Ψ)/(∂z^2)= S_s/K  ∂h/∂t. This discretizes the time element, and is very much dependent upon the diffusive properties of the aquifer. Note that S_s/K is the reciprocal of the 'hydraulic diffusivity', hence the name of the equation.


Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside? I am in O'Fallon, Missouri and today it is -15 °C (5 °F) outside. I was taught water freezes at 0 °C (32 °F). I could understand if it was exactly 0 °C (32 °F) that the water might not be turning to ice, but how can it be 15 °C (27 °F) below water's freezing point and still be liquid water? The water is still moving due to the wind, which I think shows it has no plan of freezing. How can this be?

My question may be too broad because there may be more than one reason why it isn't freezing, but I don't know of any. I tried to narrow it by giving my exact location and temperatures. It is a pond in my backyard. From what I've seen through Google, it may have something to do with crystallization rate? Thanks in advance.

Water is a rather strange substance. With most substances, the solid phase is denser than is the liquid phase. This is not the case with water. Ice is less dense than liquid water. A side effect of this effect is that liquid water very close the the freezing point is less dense than is slightly warmer water. That very cool water sinks.

Liquid fresh water achieves its maximum density at a temperature of 4 °C (40 °F). This means that a pond or lake cannot freeze until the entire body of water is cooled to 4 °C. Only then can the upper surface of the water cool to below 4 °C, and then eventually freeze.

In addition to the water itself needing to be cooled to 4 °C before freezing can commence, the water-saturated ground beneath the pond has to be cooled as well. Until then, that warmer ground will transfer heat to the pond and keep it from freezing.

How long it takes before a body of water to first start freezing depends on a number of parameters. These include the size and depth of the body of water, the nature of the ground beneath the body of water, the weather leading up to the cold weather, and windiness. The question doesn't mention the depth of the pond, but it's only been below freezing in O'fallon, Missouri for about 24 hours, and temperatures had been quite balmy before that. That 24 hours span of sub-freezing weather is more than enough time to freeze a small puddle, but certainly not a lake, and probably not even a pond.

The question also mentions that it's windy. For a body of water to freeze, it needs a cooler layer of water atop the 4 °C thermocline. Winds act to keep the water well-mixed.


What would be the temperature of earth if there was no atmosphere? I do know that the atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect),and reducing temperature extremes between day and night (the diurnal temperature variation). I wonder what temperature would earth reach if there was no atmosphere?.

According to Wikipedia an approximate average surface temperature for a bare earth is 274.5 K. This scenario is quite reasonable in my opinion as stripping the atmosphere without changing much else would (on a geological timescale) rather quickly result in a bare earth without ice caps or vegetation, causing circumstances quite close to those on the moon. (I assume the Earth's magnetic field protecting both the atmosphere and life below it has disappeared as well)

This is estimated by comparing the black body radiation of the Earth and Moon, which is then corrected for albedo (fraction of incoming radiation that is reflected) and emissivity (ability of a material to emit radiation), which are properties of a material. Since the Earth and moon are both at the same distance to the sun and made up from the same material on average, measurements of the albedo and emissivity of the moon can than be used as estimations of these properties for the Earth.

The black body radiation of the sun is calculated with the Stefan-Boltzmann law:

$$P_{\text{S,emit}} = 4\pi R_S^2 \sigma T_S^4$$

$P_{\text{S,emit}}$ is the emitted energy by the sun, $R_S$ is the radius of the sun, and $T_S$ is the temperature of the sun. The fraction of this energy recieved by the Earth is then proportional to the circular surface area facing the sun and the energy density at the distance $D$ between the Earth and the sun.

$$P_{\text{SE}} = P_{\text{S,emit}}\left(\frac{\pi R_E^2}{4\pi D^2}\right)$$

$R_E$ is the Earth's radius. Using albedo $\alpha$ the absorbed energy can be calculated:

$$P_{\text{E,abs}} = (1-\alpha)P_{\text{SE}}$$

Applying the Stefan-Boltzman law to the Earth, corrected for the emissivity $\overline{\epsilon}$, the emitted energy is then:

$$P_{\text{E,emit}} = \overline{\epsilon} 4\pi R_E^2 \sigma T_E^4$$

Assuming energy equilibrium $P_{\text{E,abs}} = P_{\text{E,emit}}$ we can now calculate $T_E$:

$$\begin{aligned}
\frac{(1-\alpha)4\pi R_S^2 \sigma T_S^4\pi R_E^2}{4\pi D^2} & = \overline{\epsilon}4\pi R_E^2 \sigma T_E^4 \\
T_E^4 & = \frac{(1-\alpha)4\pi R_S^2 \sigma T_S^4\pi R_E^2}{\overline{\epsilon}4\pi D^2 4\pi R_E^2 \sigma} \\
T_E^4 & = \frac{(1-\alpha) R_S^2 T_S^4}{ 4\overline{\epsilon}D^2  } \\
T_E & = \left( \frac{(1-\alpha) R_S^2 T_S^4}{4 \overline{\epsilon}D^2 }\right)^{\frac{1}{4}} \\
T_E & = T_S \left( \frac{(1-\alpha) R_S^2}{4 \overline{\epsilon} D^2 }\right)^{\frac{1}{4}} \\
T_E & = T_S \sqrt{ \frac{ R_S \sqrt{\frac{1-\alpha}{\overline{\epsilon}}} }{2 D } }
\end{aligned}$$

Finally we only need to insert the correct values:

$R_S = 6.96\times 10^8$ m
$T_S = 5778$ K
$D = 1.496\times 10^{11}$ m
$\alpha = 0.1054$ (assuming value of the moon)
$\overline{\epsilon} = 0.95$ (assuming value of the moon)

This gives us a temperature of 274.5 K.

Note that there are many factors that can cause local and temporal variations. For example, incoming radiation varies with latitude and season, and if the removal of the atmosphere would be caused by a dying sun that grows to engulf the earth temperatures would be much higher than this. All in all, to account for all those factors a very large model must be made that can analyse the influence of each factor, including the decrease in temperature of a dying sun etc., but that would be nearly impossible to build if only for the resources it would take to do so.

Since one of the most contested factors is the albedo after the atmosphere is removed the following graph shows how the average surface temperature changes with albedo. At an albedo of zero all incoming solar radiation is absorbed, while at 1 all radiation is reflected. Note that the temperature of 0K is an effect of the assumed equilibrium between incoming and emitted radiation, which will not hold at that point. As said above, the albedo for a bare earth will be approximately 0.1, while current values on average range from 0.3-0.4, largely contributed to by clouds. An average for the albedo of the Earth in its current vegetated state, but without clouds I haven't been able to find.

As stated by @ardie-j in his answer, another possible fate of the Earth could be that it gets covered in ice, as another Snowball Earth Event. In that case the albedo would rise to levels ranging from 0.4-0.9, resulting in a drastically cooler Earth.


gamma ray burst, extinction-level event From this subsection in Wikipedia's aricle on extinction event:

  A nearby gamma-ray burst (less than 6000 light years away) would be powerful enough to destroy the Earth's ozone layer, leaving organisms vulnerable to ultraviolet radiation from the sun.[92] Gamma ray bursts are fairly rare, occurring only a few times in a given galaxy per million years.[93] It has been suggested that a supernova or gamma ray burst caused the End-Ordovician extinction.[94]

Does this mean if this were to occur it would take 6000 years for the gamma ray burst to destroy our ozone (potentially)?

As bon noted in the comments, that it the time it would take the gamma rays to reach Earth. Gamme rays travel at the same speed as all other forms of electromagnetic radiation, including visible light, so we will not have any warning. This kind of makes the "6000" number meaningless. We will know that the star exploded and the gamme rays will reach earth at the same time. The destruction of ozone will then probably be instantaneous (on a geological time scale).

From your quote:

  It has been suggested that a supernova or gamma ray burst caused the End-Ordovician extinction.

It has been suggested because there was no other plausible terrestrial cause for the mass extinction, so people started to look at extra-terrestrial causes. But a paper published earlier this year documents a mercury anomaly associated with the extinction event. This gives strong evidence for a volcanic cause for the extinction (similar to the P-T or K-Pg events), and there is no need to make up a gamma-ray burst.

David S. Jones, Anna M. Martini, David A. Fike, and Kunio Kaiho: A volcanic trigger for the Late Ordovician mass extinction? Mercury data from south China and Laurentia. Geology, July 2017, v. 45, p. 631-634, 2017, doi:10.1130/G38940.1


If a ship on its way to Germany from Norway sank, where will the survivors likely end up? a) what are the chances, taking into account influencing factors like ocean currents, that these survivors will end up on English shores?

b) what are the chances, again taking into account all influencing factors, that these survivors will end up anywhere near Africa's rainforest/jungle region?

The survivors would probably end up in Jutland or Norway, maybe Sweden due to the currents.

CC BY-SA 3.0

The main wind pattern is also western, but with prevailing eastern winds, they might end up in Scotland, depending on the vessel. The Jutlandic coast has experienced a large number of shipwrecks in the past.

DMI

Even if a boat gets out on the open ocean, the Gulf stream flows northeast, so there are very small chances to get to Sub-Saharan Africa.

So the answer would be: (a), very small but depending on the survivors' ability to navigate and the wind direction. (b) None.

Here is a sad account of the North Sea currents


What is that drain east of newfoundland On Google Maps I just found a drain east of Newfoundland:

More details at https://www.scribblemaps.com/maps/view/What_is_that/Jafix1

I wonder what that could be?

I heard about issues from different datasources which can occur when Google mixes data from NOAA or other sources with their own. Or could that be issued by a giant ice mountain drifting southwards? Or from the last ice age?

It is an artifact of the processing software when it processes Multibeam Bathymetric Survey data.
You can get the lines of the different surveys from NGBC at NOAA (https://maps.ngdc.noaa.gov/viewers/bathymetry/). As you can see in the image below both lines you see in your example correspond to multibeam data. In the area there is a fair amount of single-beam bathymetry, but the multibeam bathy is often weighted differently creating artifacts in some cases.
The GEBCO bathymetry does not contain the artifact.


Were Carboniferous plants more efficient sequestering $\ce{CO2}$ than present plants? The Carboniferous was a period where CO2 levels fell drastically.

Source: Geologic history of seawater: A MAGic approach to carbon chemistry and ocean ventilation
I think the main reasons are tectonic settings and the formation of coal deposits with the arrival of lignite-rich plants that bacteria didn't know yet how to decompose.
My question here is:
Forgetting Carboniferous plants were efficient sequestrating CO2 forming coal deposits after dying, were living Carboniferous plants more efficient sequestering CO2 than present plants?
Meaning, would a Carboniferous forest be more efficient than present forests to sequestrate CO2 nowadays?

Probably not.
The biological pathways to make lignin is the same in all plants so there is no reasons to believe they would be better. If anything modern trees as a whole may be better since they survive in  larger range of environments and very dense wooded trees exist. In addition without defenses against modern wood decomposers Carboniferous plants may have a hard time surviving in the modern world.


Help interpreting a wind rose diagram Can someone comment on technical explanation of the wind rose attached?

I can understand the wind is blowing between WNW & SSW with speed of 7-11 km/h. For frequency of 11-16 km/h its blowing from SW & SSW.
For frequency of 4-7 km/h its blowing between WNW & ESE?

Is this all or some info I am missing?
What do the spikes mean?

No, you've misunderstood it. There's lots of information you're missing. Every data point is information, and you've listed a tiny proportion of them.

Furthermore, 4-7 km/h and 11-16 km/h aren't frequencies at all, they're wind speeds. The distance from the centre gives you the frequency.

So the spike towards N means that North winds are much much more frequent than the NNW and NNE winds. There may be some protection in those directions such that the winds that would come from there, are actually getting channelled to come from the North instead. Or there's a particular time-of-day effect, or a recording artifact, or one of a dozen other explanations that only someone with more information about the site and the data collection could assess.

However, the fastest winds don't blow from that direction at all: they're all coming from the quadrant between S and W.


Velocity gradient of surface ocean current in dephts How much speed of surface currents decrease in ocean depth? Approximately? I am wondering if there is any significant gradient within the top 30m ocean layer? Can this be theoretically calculated?

Yes, the speed of currents varies with depth.

In the case of shallow, coastal water, the flow is retarted by friction at the seabed, so it is slowest at the seabed and usually has a curve of increasing speed towards the surface.

This curve can theoretically be calculated, but in practice it is very sensitive to things like the material and shape of the seabed, wind and waves near the surface, and so forth, so while estimates can be made from theory, it's usually better to measure it.

Approximations are often made using a "power law" such as

$u_1 = u_2 \left( \frac{z_2}{z_1} \right)^{\frac{1}{\alpha}}$

where $u_1$ and $u_2$ are the speeds at distances $z_1$ and $z_2$ above the seabed respectively, and $\alpha$ is an arbitrary value often between 5 and 7.
This figure, from Lewis et al. 2017 (creative commons licensed), illustrates a number of such theoretical curves with different values of $\alpha$.

In deeper oceans this mechanism will only apply close to the seabed; however, far more complex systems can come into play, with different water bodies moving in (potentially) different directions. Possibly others with more expertise in ocean dynamics can address that case.


What did tunnel digging teach us about the formation of chains of mountains? Since tunnelling is like making a giant horizontal core sample, what did the analysis of the extracted rocks teach us? Is the inside homogeneous or layered, are there "deformations", etc?

Tunnels have provided nothing more than what was learned from conventional geological drilling and surface mapping. Tunnels provide supplemental information. Very rarely do they provide "make or break" information that is pivotal to geological understanding on a large scale.

A tunnel is a lateral large diameter hole. Geological drilling produces small diameter holes, whose orientation can be lateral, vertical or anything in between. A sample of rock is take by both.

By using in-hole surveys and noting from where, within a hole, a sample was taken from it is possible to know where the rock sample came from. This is useful for creating geological maps of the region. It is even possible to place ground stress measuring devices in both drill holes and tunnels.

The mass of material taken from a hole, whether it be a geological drill hole or a tunnel is not particularly significant in expanding knowledge. More knowledge can be gained from multiple small samples taken over a large area.

Tunnels do give geologists the advantage of walking through a rock mass and seeing some structures like faults. But if the tunnel hasn't intersected a structure then the geologists may not know about it.

Your question is a bit like asking "what can be learn about a country by just walking along its roads". Additional information can be gained by walking off track, navigating rivers, flying over the country and talking to the inhabitants.

Tunnels provide some information. It is useful information, but multiple sources of information given us a better understanding.


Why is uranium only in the crust, really? As I know, uranium is currently thought that it is mainly in the crust and not in the core or in the mantle. The reason for that it is a siderophile element which means it won't be solved in molten iron. Recent geoneutrino experiments seems to support this view, too.

But, according to this answer, the solubility of Uranium in the Earth Core is between 2ppm and 6ppm. This is not a really high value, but it is still much more as the mean proportion of the Uranium in the whole Earth.

So, first I think the general siderophility of Uranium is not a reason to not have a lot of cubic kilometers of solved U in the outer core.

Second, what I think: trying to mix unmixable liquids they we will have separate phases of solutions in the order of their density. Also, trying to mix uranium and iron liquid, we will have

A phase of solution of uranium in iron (higher)
Below that, a solution of iron in uranium.

At least one of them will be also a saturated solution.

So, I don't see any reason, why wouldn't the Uranium concentrate in the outer crust. Or there is some mechanism out of these as well?

(tl;dr below)

First, a correction. Siderophile elements are "iron-loving" elements, those that go in the core with the Fe-Ni liquid. Uranium is lithophile, or "rock-loving". It partitions to silicate rocky material (i.e. mantle and crust) relative to the core.

Secondly,

  But, according to this answer, the solubility of Uranium in the Earth
  Core is between 2ppm and 6ppm.

You have to understand where this is coming from. That answer is based on this paper, which experimentally measured how much U is in the Fe phase, coexisting with a silicate phase of peridotite composition (which is an approximation of the mantle composition). If you look at their Table 3 (page 14) and Figure 8 (page 17) you can see that the $D_\rm{U}$ values range from almost 0 to around 0.03. This value mean the ratio of U in the metal phase relative to the silicate phase. So even in the most extreme case, you're going to have 30 times more U in the mantle than in the core. And in their experimental setup they used wt % amounts of U in the starting material, much much more than exists in the Earth, so you eventually get a considerable amount in the Fe-metal phase. This does not mean that this is the amount that is present there now, inside the Earth.

The truth is, we do not know how much U is there in the core. And this research papers shows that whatever amount there is, there will be more in the mantle. There will be even more in the crust, because U is an incompatible element in partial melting of the mantle. See this Q&A for more information about that:

What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?

Also related, also read the comments:

What percent of the Earth's core is uranium?

  Second, what I think: trying to mix unmixable liquids they we will
  have separate phases of solutions in the order of their density...

You have to differentiate solubility from partitioning. Solubility is how much of x (let's say U) you can put in y (let's say Fe) before you saturate a separate phase instead of one. Partitioning is when you have two phases x and y (let's say Fe-liquid and silicate), how much a third component z (let's say U) will dissolve in each. The paper linked to before was discussing partitioning. In terms of solubility, there is a complete solution of liquid U and Fe when the temperature is high enough (such as in the Earth's core). Even if there's not, a ppm amount of U in liquid Fe is not enough to saturate a separate liquid U phase, so density doesn't matter. If it's all one phase, density plays no role. If you have a solution of NaCl and KCl in water, it's all homogeneous. The K doesn't sink because it's denser.

tl;dr

We do not know how much U is in the core. We do know that whatever amount of U goes in the core, more U will be in the silicate mantle. When you melt the mantle to produce magmas that form the crust, it concentrates U even more, and depletes the mantle of U.


Area reduction factor reference for precipitation For a large catchment (>1000ha) I'm looking for some method to use a area reduction factor to adapt precipitation values. I have a large dataset of daily precipitation values but I have to use some kind of adaptation. I have don't enough data to calibrate a rainfall runoff model.

I have looked in some literature but there is little generally usable information. Does someone has a good reference for me? Thanks in advance.

The answer depends on whether your data is from a single gauge or a network of gauges, and whether you have storm tracking data or not. Sounds to me like you have daily precip at a single gauge without much more information. If you know the annual average precipitation in the basin then a simple area reduction factor (ARF) calculation is basically the ratio of the annual average gauge precipitation over the basin average.

I am not too familiar with the literature on this, but this report seems like a good starting point for background info.


What is the difference between the freezing level and 0C isotherm in NOAA's GFS? I'm playing around with NOAA's GFS forecast data and I see that it contains both a "0C isotherm level" and a "Highest tropospheric freezing level".

Could someone tell me the difference between these two levels? I'd assume they are the same except in the case of an inversion.

Various processes affect the freezing point. Both CCN (cloud condensation nuclei) characteristics and drop size affect the freezing point.


Why does NOAA no longer provide sunshine data? It seems like NOAA used to provide sunshine data from the US weather stations but no longer does.  Is there a reason that was discontinued?

It was not discontinued

Using the Climate Data Online tool from NOAA's website, I was able to get sunshine data through March 1st of this year for both major airports in my metropolitan area.

Sunshine data is relatively restricted geographically compared to other datasets like temperature and precipitation (for those I counted 7 stations in my metro area), but you should be able to retrieve data from any major airport.


Why does dew accumlate on only one side of my car? Many days I walk out to my car to go to work and notice my windows are fogged up, I believe due to dew (haha homophones). When I am at my mother's house(O'Fallon, MO), all Windows get fogged up. When I am at my father's house (Saint Charles, MO), only one side of the car is fogged up.

This is kind of a two-part question. 1) How does dew accumulate? 2) Why would it only accumulate on one side of my car?

I suspect it has to do with the fact the side that does not fog up faces a tree. This is very curious to me. Since I am not sure what else is needed to answer my question, I will update as comments come in.

The formation of dew is due to atmospheric moisture and temperature.

Given that dew forms on all sides of your car at your mother's house, this makes me think the car is more exposed at you mother's house so that the car is uniformly cold and the temperature of the car is at, or below, the dew point.

With dew only forming on one side of the car when at your father's house, this tends to infer there is a temperature difference between each side of the car; with the side of the car on which due forms being colder.

You mention that dew does not form on the side of the car facing a tree. If the tree is sufficiently large and leafy (bushy) and the car is close enough to the tree, the tree can shield the car from the cold air thus making that side of the car slightly warmer than the other side of the car. As long as the temperature is above the dew point, due will not form.

Dew point varies for atmospheric moisture content, temperature and air pressure.


Determining hardness using teeth So I know scratch tests are pretty common to quickly get an estimate of a rocks hardness. Also tooth enamel is a common material with a 5 on mohs scale. So far so good, but what shocked me is that I heard students on field trips actually use their own teeth sometimes to determine hardness.

The obvious explanation is that I've been fooled, which I expect will be the answer.

But if this is really true, how do your teeth survive? Or is it just an occupational hazard that you're going to need dentures before your thirties as a geologist?

Disclaimer: this question comes from a story someone told me some time ago, whose girlfriend studied earth sciences. I found it implausible then, but it keeps bugging me and I can't find information on this except that gold miners probably routinely lost their teeth during the 19th century.

No, teeth are not used to determine hardness. That would be incredibly stupid. What teeth are used for is distinguishing silt from clay.

When dealing with very fine grained rocks you might be interested in the relative proportions of clay-sized particles and silt-sized particles in the rock. This is very hard to do, but surprisingly quite easy when you try to put some between your teeth. Clays will have a smooth, paste-like, feeling, whereas silt will feel like fine grained sand. With enough experience you will be able to give a rough estimate of the proportions of the minerals.

Also notice this related question:

When can taste be used to help identify rocks?


How do scientists reconstruct pre Cretaceous continent if all plates that are currently left are younger than Cretaceous? I have read that the oldest oceanic plate that we see today is from the Cretaceous period. If so, how do scientists reconstruct plate movements and continental structure pre Cretaceous? And aren't all fossils before Cretaceous lost?

Why are we able to deduct geology information pre Cretaceous? And what is the oldest period we are able to gain information from?

You forgot about continents

First of all, it's necessary to point out the false premise in your question: It is not true that "all plates that are currently left are younger than Cretaceous".  There is a near-continuous record of rocks stretching all the way back to the Hadean Eon 4 billion years ago.  And there are older crystals called zircons that are found as inclusions in younger rocks.

The thing is, these rocks are on land, part of continental crust. Your question seems to be unaware of the existence of  continental crust. Of course, since you're not currently sitting at the bottom of the ocean, you're on top of continental crust right now. Most of the big tectonic plates are part oceanic and part continental.

Continents have been built up little by little over geological time. Their rocks are a mixed-up jigsaw puzzle of various types and ages. It's the geologist's job to figure out how those pieces fit together.

Here's just a taste, and it doesn't even show the complexity of the puzzle in North America by a long shot:

(courtesy of United States Geological Survey, via Wikimedia Commons)

It is true that the oceanic plates are mostly destroyed by subduction, but the oceanic crust has to go beneath something, and that's often a continent. Besides, subduction helps make continents grow:

not all of the rock is subducted: some seafloor sediments are scraped off and piled against continental margins
The top layers of rock that are subducted melt, and the melted rock bubbles its way up through the overlying crust, producing plutons and volcanic arcs. Sometimes these are on continents (such as the Cascades and Andes) so their rocks directly add mass to them.
When the volcanoes are out in the ocean, the subduction process pulls them into continents and they get cemented to the edge. Sometimes they form little mini- continents (such as Japan and New Zealand).

The oldest oceanic crust currently at the seafloor is in the eastern Mediterranean. In an article in Nature Geoscience Roi Granot of Ben-Gurion University of the Negev suggests that the [Herodotus Basin] is a remnant of ancient Tethys Ocean, having formed up to 340 Ma during the Early Carboniferous period. Most oceanic crust is 200 million years old (Jurassic) or younger.  They're an important part of putting the puzzle together, but as I stated at the beginning of my answer, the geological record is much older, because of continental rocks.

Finally, there is really old oceanic crust in the form of ophiolites, which are bits of oceanic crust that have been incorporated into continents.  Since they're no longer part of the oceanic conveyor belt, some can be quite old. The oldest is about 3.8 billion years old.


What "blobs" of molten material in Earth's interior are responsible for the rapidly moving north pole? Where are these blobs exactly? IFL Science's Earth's North Magnetic Pole Is Heading Towards Siberia – And Scientists Now Know Why explains that the motion of Earth's north magnetic pole can be understood as follows:

  A new study, published this week in the journal Nature Geoscience, argues the changes could be explained by the to-ing and fro-ing between two magnetic "blobs" of molten material in the planet's interior, causing a titanic shift of its magnetic field.

See also The BBC's Scientists explain magnetic pole's wanderings.

Are these blobs sufficiently distinct to describe their locations somehow, perhaps with spherical coordinates like latitude, longitude and distance from the center from the Earth, or some cartesian scheme?

Where are they?

The "blobs" referred to in the IFLS article are, more correctly, areas of strong magnetic flux at the Earth's surface. The term "blob" is not scientifically significant, it just refers to a region where the magnetic field coming from Earth's core is stronger than elsewhere. Often we'd depict the magnetic field with a contour map of field strength, giving peaks and troughs of strong and weak field the appearance of "blobs" or patches, like this summary image from the publication in question:

(source: P. Livermore, via ESA: http://www.esa.int/Applications/Observing_the_Earth/Swarm/Magnetic_north_and_the_elongating_blob)

The maps show the radial magnetic field strength at Earth's surface in 1999, and then the field in 2019, this time with a trail showing the movement of the North magnetic dip pole (the star) since 1999. The two "blobs" of stronger field can be seen to change, the one over Siberia gets bigger and pulls the pole towards it, away from the now smaller Canadian one.

These "blobs" of strong field on the maps aren't "molten material in Earth's interior", but we can infer from maps like this what the field would look like at the surface of the outer core, and then from there what the movement of the material within the outer core might have been in order to generate the magnetic field we've observed. This is thanks to (math heavy :( ) frozen-flux theorem, that essentially says magnetic field is "frozen" into the iron-rich fluid at the surface of the Earth's outer core, so acts like a tracer for the fluid movement at the top of the outer core.

For an idea of what the flow (labelled "|U|") of material at the surface of the core might look like during the last 20 years to produce the field (labelled "Br", note the flipped color scheme), here are stills from the same model cited by the publication's authors of the field and flow at the core surface in 1999 and 2017. The Canadian "blob" gets stretched out and weaker relative to a strengthening Siberian "blob", as the flow speeds up under Canada:

(Source: https://geodyn.univ-grenoble-alpes.fr/, play with the great visualisations, but the animations are enormous files!)

So yes, you can map the distinct location of these "blobs" of strong field (though only outside the core), but bear in mind the maps are plotted with largely irrelevant choices of contour levels -- the field is continuous and varies smoothly, it's been drawn like this to highlight the "blobs" more clearly.

(Edit: added images of field and flow at the core surface to clarify, and make this answer a bit long...)


How are jet streaks formed? "Jet Streak Dynamics I: The four-quadrant model" - explains their effects on frontogenesis.

But how are they formed to begin with?

In the blog post, "[They] start with a pressure gradient." So I'll discuss how a pressure gradient force develops at the jet streak level and why it develops at the jet streak level.

First let's go over some basics. From the meteorological perspective, one can think of pressure as the amount of air mass above a point (gravity provides the acceleration). So high pressure means relative large amounts of air mass above a point and low pressure means a relatively low amount of air mass above a point.

Now, think of two columns of air that start at surface and go into space. One column is really cold and the other column is really warm. Warm air is less dense than the cold air. If the cold air column and the warm column have the same amount of mass, the warm air column will be taller. If the two columns have the same mass, the surface pressure of the two columns will be the same.

If we travel up these two columns we would expect the pressure to decrease with them as the amount of mass above us decreases. The pressure in the cold column would decrease faster than the mass in the warm column as we travel up the columns. This means at a certain height, say 10 km, the pressure in the warm column will be much greater than in the cold column (see image below). This is a pressure gradient and causes the jet streak in the link you posted.

So how do we get cold air column next to warm columns? Those are fronts! A northern hemisphere warm front typically will have cold air to the north and warm air to the south. So the pressure gradient force at 10 km above the surface (about jet streak level) will be from south to north (note: the pressure gradient is from north to south in this example). Wind wants to go from south to north but is deflected by the Coriolis force as explained in the blog post. Now check out a weather map, you'll find the jet streak will be over a surface warm front!

Now, as we keep going up, the maximum pressure gradient will be at the jet streak level. Above the jet streak level, is the stratosphere which contains ozone. O-zone absorbs radiation and warms the air around it. The stratosphere starts at a lower altitude over cold surface air, so our pressure gradient begins to shrink above the jet streak.

In other words, the jet streak is at the maximum pressure gradient. Which occurs above the boundary of cold air and warm at the surface.

From: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter10/graphics/pf_xsect2.free.gif

This picture does a good job of showing how cold air will have lower pressure than warm air aloft.

Edit: I should mention, fronts and jet streaks are kinda a chicken and egg scenarios. They each cause each other to some degree.


Why is the temperature between the earth core and surface not distributed linearly? So I read somewhere that the inner core temperature of Earth might be as high as 7000 °C.

Depending on the composition of the different layers towards the surface, the temperature should decline until the surface temperature of the air, at about average 14 °C, is reached.

This does however not seem to be the case as the temperature at first gets colder if one starts digging?

How can this be explained?

And please excuse any naivety on my behalf as I´m no scientist.

The temperature does indeed increase with depth, something that is a problem in deep mines or deep drilling, but a benefit for geotermal heating. The heat originates mostly from radioactive decay, but there is also a fraction of primordial heat from the formation of the Earth.

As a rule of thumb, geologists often assume 25°C/km temperature increasements within continental plates, but steeper increasements in oceanic plates or volcanic regions. The temperature curve is not constant, however. Due to the convection, the temperature increases slower with depth in the mantle and outer core. In that sense, the crust is an isolating cover. The temperature also varies due to subductions, the dynamics of the mantle and radioactivity within the crust.

The shallow soil temperature and the temperature in the air depend mostly on the insolation, the radiation heat from the sun. The average annual solar isolation is 1361 $W/m^2$ but only 20-500 $mW/m^2$ heat flux comes from Earth's internal heat production. However, this tiny fraction can sometime sbe important, e.g. to understand basal melting of ice sheets and glaciers.

Temperature gradient from crust to core. Recent research have improved the accuracy, but the principle in the figure remains (Annual Review of Earth and Planetary Sciences, 24(1), 15–40)

So why do you experience the temperature colder underground when you are digging?

The temperature at depth is the average temperature for day and night or even the year. The energy from the sun reaches only the uppermost soil layer that absorbs heat but the thermal conductivity is relatively low and it will not transport the heat down. The ground is reluctant to change its temperature regardless of variations on the surface.

How strongly you experience the temperature difference depends on where in the world you are and the local conditions. In some areas, the ground remains frozen, known as permafrost, even as the temperatures in the air can be pleasant during the summer and the surface layer melts. The depth of the suggests that it's been formed over a long time. It reaches down to the depth where the mean temperature over hundreds or thousands of years is 0°C. At larger depths, the heat from the Earth's interior takes over and melts the frost.

Temperature in the active layer and permafrost. The thickness of active layer is less than a couple of meters and the thickness of the permafrost depends on its age, the bedrock and the distance to the coast. (By German Wikipedia contributor, "HylgeriaK")

See the plot, linked by @JeopardyTempest in the comments to better understand the variations. Plotted on another scale and depth, annual variations would probably be seen as well.


Do other terrestrial planets have "earthquakes"? I know some planets have storms akin to what we have on Earth although obviously varying in nature.

I was wondering if other planets have earthquakes? Since this comes down to plate tectonics (right?), I guess I am also asking if other planets have plate tectonics.

Obviously, a planet like Uranus or Neptune wouldn't because they are gas, so I am restricting it to terrestrial ones.

I tried to look this up on Wikipedia, but I couldn't think of a word besides non-earthquake or just quake but those didn't turn up any results.

What frequency do different kinds of seismic activity appear throughout the universe?

For terminology, "Earth"quakes might be replaced with "seismic activity" since earthquakes are by definition restricted to the Earth.

Technically speaking the other terrestrial planets in our solar system are not active in terms of plate tectonics.  Mercury undergoes rapid heating/cooling depending on its rotation and exposure to the Sun which must lead to some type of seismic activity, though likely very small magnitude.  I don't know of any seismic anomalies recorded on Venus or Mars but certainly there must be some type of activity from time to time due to changes in magma.  Magma - related quakes, though, are typically not as strong as quakes from the dynamics of plate tectonics.  For instance, Hawaii has seismic activity due to the volcanos, which produce maximum seismic activity that is orders of magnitude less than what two plates (e.g. a fault line) rubbing against eachother produce.  Though, the magmatic processes lead to a higher quake frequency.

I would wager that the moon of Jupiter, Io, and Earth have the strongest seismic activity in our solar system.


Does the amount of rainfall relate to temperatures of a place? Does the amount of rainfall relate to temperatures of a place? Is the amount of rainfall related to the maximum mean temperature of a place?

Yes, with exceptions

Rainfall is related to temperature. However temperature is not the only thing that dictates rainfull.

In general, the more hot a place is, the more water evaporates and the more rainfall is able to be produced.

For example, the equator has a belt of rain-forests precisely because it receives the highest amount of heat from the sun and thus high amounts of rain-fall.

However, not all hot places make a lot of rain. Deserts occur when there is a lack of rain fall. Yet deserts can occur in cold temperatures (the north pole) and hot temperatures (Sahara desert).

To sum, temperature is certainly related to the amount of rainfall. However, you can't just presume the level of rainfall by temperature as many other factors are invovled.


Are there General Circulation Models that can simulate the atmosphere of Venus? I would like to know what would happen with the atmosphere of Venus when it gets tidally locked, i.e. when one side would perpetually face the Sun.
Probably a thermal low would be at the subsolar region then.

At the surface Venus has an atmospheric pressure of 92 atm. and a temperature of 462$⁰$ C.

Are there General Circulation Models or Global Climate Models that can handle such input parameters ?

If so, are there GCM users (groups, universities etc.) who could run a tidally locked Venus simulation ?

I'm not sure of their current status, but I read some papers based on these models a few years ago:

Oxford Planetary Unified Model System for Venus (OPUS-V), which is based on an old version of the UK Met Office climate model, HadCM3 (paper from 2016).
ROCKE-3D at Nasa GISS, which is based on an old version of the GISS ModelE2‐R climate model (blog article and paper from 2016).

It looks like the introduction of Yamamoto et al (2019) has a more up-to-date summary of the current set of models, and there's quite a healthy selection from groups around the world.