Is there any mineral identification techniques that works for all minerals? Are there any mineral identification techniques that work for all minerals(non-metallic/metallic), so that an electronic device could be made to distinguish between all minerals?

Yes, it is called X-ray diffraction (XRD). It is done by machines that look like this:

I'm not sure this is in the scope of your electronic engineering project.


Can rocks have pressure signatures? Since rocks can have magnetic signatures, as is the case with paleomagnetism, can they store past pressures also?

For example, when researchers are trying to determine past ocean levels, they usually look at isotopes. But is there any way they can look at rock morphology to see how high sea levels may have been (maybe a more compressed rock meant higher pressures, meaning higher sea levels and vice versa)?

Since rocks can have magnetic signatures, as is the case with paleomagnetism, can they store past pressures also?

Yes, but not directly, and it is very hard to know the exact pressure (in contrast with paleomagnetism where you can actually get a nice number).

One way to do it is to simply look at the minerals you have in the rock. Some minerals exist only in a certain range of pressures. The best and most known example is the two polymorphs of carbon: graphite and diamond. If you find a rock with diamonds in it then you know that (at least the diamonds) formed at great depth. There are many other mineral transformations that depend on pressure. Andalusite is low pressure whereas kyanite is high pressure. Plagioclase is low pressure, spinel is intermediate pressure and garnet is high pressure. You can look up images of those minerals for some eye candy! Note that I'm using the words "low" and "high" quite vaguely, as everything is relative and the exact numbers are not important for this case.

Another way of finding the pressure of a rock formation is by using the chemical compositions of the minerals in it. This is basically an improved version of the previous method. Instead of having a certain mineral assemblage transform to a second assemblage, we take two coexisting minerals. If we know how a certain element (for example magnesium or aluminum or whatever) behaves in a certain fashion relative to the pressure, we can measure that element in both minerals and find out the pressure.

A third way is to look at a thing called fluid inclusions. These are tiny bubbles of liquid or gas (or something in between, the distinction may be fuzzy at high pressures and temperatures), trapped in a mineral when it was forming. This is essentially a tiny pressure vessel, so using all kinds of methods we can figure out what was the pressure during that time. Here's a picture of how it looks under the microscope:

source: http://rohmin.unileoben.ac.at/de/3388/

  But is there any way they can look at rock morphology to see how high sea levels may have been?

Not using these methods. The problem is sensitivity. I was talking to you about diamond and graphite - this is extremely deep in the Earth. The pressure of adding a few metres of ocean on top of it are definitely not even going to tickle that transformation. Furthermore, for this to actually be effective, the rocks have to be directly on the seafloor. Once you start burying them in the sediment, you have additional pressure on top of them. A general rule of thumb is 100 metres of additional rock pressure equal 300 metres of water pressure. How would you know how much rock was on top of it? And as the rock gets buried deeper, how would you know what time frame your measurement represents?

So in short, no. We can't do it. There are, however, other methods of figuring out sea levels without using pressures.


Technique to delete spin-up frames from WRF I'm a user of WRF V3.5 aiming at  meteorological simulation.
Sometimes, I'll run the model for a long period.

My attempt

I split the long period(e.g 1 year) into serval short ones.

For example:

 ## WPS namelist.wps
 start_date = '2014-01-01_06:00:00'
 end_date   = '2014-01-31_23:00:00'

 ## WRF run period setting in .csh file.
 set year = "2014"
 foreach strtime (010106010512 010500011012 011000011512 011500012012 012000012512 012500013012 013000020100)

 set smon = `echo ${strtime}|cut -c1-2`
 set sday = `echo ${strtime}|cut -c3-4`
 set shr  = `echo ${strtime}|cut -c5-6`
 set emon = `echo ${strtime}|cut -c7-8`
 set eday = `echo ${strtime}|cut -c9-10`
 set ehr  = `echo ${strtime}|cut -c11-12`

 &time_control
 run_days                            = 0,
 run_hours                           = 132,
 run_minutes                         = 0,
 run_seconds                         = 0,
 start_year                          = ${year},${year},
 start_month                         = ${smon},${smon},
 start_day                           = ${sday},${sday},
 start_hour                          = ${shr},${shr},
 start_minute                        = 00,00,
 start_second                        = 00,00,
 end_year                            = ${year},${year},
 end_month                           = ${emon},${emon},
 end_day                             = ${eday},${eday},
 end_hour                            = ${ehr},${ehr},
 end_minute                          = 00,00,
 end_second                          = 00,00,
 interval_seconds                    = 21600

In these short period, I set the first 12-h as the spinning period(except the start one.)

This is the schematics of the temporal  modeling setup which I clipped from the Internet.

http://i12.tietuku.cn/afd906ddd823ddd6.png

Result

It generate 8 .nc file which each contain 132 frames of data.
For now, I use the The netCDF Operators(NCO) to deal with the output files.

Using ncks to delete the first 12-h frames for each file separately.
Using ncrcatto concat all 8 .nc files together to get one file represent the whole simulation period.

Problem

I was using this method for a while. But when the amount of files are huge, it really a dump approach.

Are there someone offering your approaches to dealing with spin-up data deletion?

My target

The model can generate only one file which contain all the simulation period.
The spin-up time can be covered by last file's frames automatically.

Update: Wish you share your approaches!

Here is my  present approach.

All wrfout-files are located in the same path.
Using pynco in python loop to split the spin-up dataframe

import glob
nco = Nco()
for fn in glob.iglob('*.nc'):
    filename, extname = os.path.splitext(fn)
    output_fn = filename[11:22] + str(int(filename[22:24]) + 12) + extname
    nco.ncks(input=fn, output=output_fn, dimension='Time,13,')

The input shows like: 2014-04-04_12.nc(120 frame inside)
The output shows like:wrfout_2014-04-04_00:00:00.nc(133 frame inside)


How does anthropogenic heating affect global warming? Anthropogenic-sourced greenhouse gases are commonly cited as the main source for human-caused climate change. However, something that I never see discussed is the actual heat produced by human activities. It could be that it's negligible, but I'm still curious to see quantitative data.

For example, a running engine in a vehicle produces $\ce{CO2}$ due to fuel combustion, but the engine also produces heat. What about heat produced from ovens, fireplaces, incandescent lighting, etc.? Ignoring the carbon footprint of such activities, can the heat alone be sufficient to affect the atmosphere on a global scale?

A recent study by Chen et al. (2014) in the article Anthropogenic Heat Release: Estimation of Global Distribution and
Possible Climate Effect defined the heat release as you described as being Anthropogenic heat release (AHR), and has it basis as a product of economic prosperity, which leads to energy usage and excess heat produced - usually in large cities globally - this is sometimes referred to as 'waste heat'.

In their research, Chen et al  report on an earlier global estimate made by Chen and Shi, 2012:

Globally, the estimated AHR is 0.03 Wm$^{-2}$
Over land, this average becomes 0.10 Wm$^{-2}$

Although, globally, these amounts are considerably less than that from $\ce{CO2}$ emissions, they still add to the problem - especially as the rate of urbanisation, hence the use of heat generating appliances is increasing rapidly, this value will become more significant.

However on a regional scale, over large cities for example, such as Tokyo, the effects of AHR are more profound.  In and around the region around Tokyo city, the AHR can exceed 400 Wm$^{-2}$.  So what are the consequences of this flux?  Most of it causes regional effects, in particular (from Chen et al.):

Can influence urban climates and is a significant contributor to the urban heat island, which amongst other things can affect regional rain patterns.
Can affect the dynamics and thermodynamics of urban boundary layers.
Can influence the reaction rates and types of emitted aerosol and particulate species.

All of which have a compounding effect in the regional and to a lesser degree, global environment, that Chen et al. attribute to as being a cause of a 1-2K temperature rise in high altitude areas in Eurasia and North America and as a disrupting influence in global atmospheric circulation.

Edit 28/2/2016: There is an interesting blog post about a similar phenomenon: Dubai construction alters local climate

Additional references

Chen, B., and G.-Y. Shi, 2012: Estimation of the distribution
of global anthropogenic heat flux. Atmos. Oceanic
Sci. Lett., 5, 108–112.


Why are metals so separated in the Earths crust? I find it very surprising that metal ore deposits are so separate, and unevenly separated on the Earth.

I do understand that there were various different conditions at some point in time in the places where ore deposits emerged, and the places were somewhat randomly distributed.

But how is it that there so many different conditions happening that all have fundamentally different effects? I would expect many different conditions, that can be grouped in much fewer types regarding the practical effect of the condition.

Or is exactly that the case, and what is surprising is only the numbers involved?

There are active geological processes that lead to separation of mineral constituents. A source material that contains specific primary minerals, with some transport mechanism (eg convection or liquid flows) to physically separate them and 'trapping' conditions that allow them to accumulate are all required. Processes that result in minerals being separated from the source material include  -

Magmatic - (within molten and partly molten magmas). Differential melting will allow specific minerals to melt and be squeezed out separately. Differential crystallisation will allow some minerals in a mixture to crystallise within a molten mass and (with changing temperature and/or pressure) to separate and reform as crystals and precipitate separately in more concentrated form in sediments at the base of a molten mass (or to rise where they are lower density than the surrounding material). Some materials can separate in their molten state, because they are immiscible (they don't mix or dissolve within each other), with similar separation because of differing density or pressure squeezing them out and solidify in concentrated forms.

Hydrothermal - minerals dissolving (usually in association with salts), with different temperature and pressures dissolving minerals preferentially. As liquid they can travel and come into contact with other minerals, resulting in chemical reactions, with potential for further differentiation.  Similar to differential crystallisation in magmas, specific minerals will crystallise and precipitate differentially out of concentrated water based solutions. Lots of sulphide mineral ore bodies were formed this way.

Physical process like erosion and sedimentation also separate and concentrate existing minerals.

(Answer in part from Wikipedia  - Ore genesis).


Severe storm predictions: What meteorological considerations go into hazard assessments? In the United States the National Weather Service (NWS) Storm Prediction Center (SPC) now has 5 categories for the threat of severe storms.  These five categories replaced the previous three categories of slight, moderate, and high risk in October 2014.

Source: http://www.spc.noaa.gov/new/images/Outlook-category-descriptions.png

The first time I heard our local station talking about slight, marginal, and enhanced risk I had no idea which was worse- nor did anybody else around me at the time.  After doing some research I understand the differences but still don't necessarily remember which is worse, whereas the previous slight, moderate, and high risk categories were pretty much self explanatory.

What additional meteorological information is presented in the additional categories that may affect how the general public reacts to the threat?  I'm also wondering how these categories compare to the information given in other countries?

The SPC's changeover announcement webpage offers very useful information on the change, and is central to this answer...

Correction:
There were actually 4 categories prior to the change.  The SPC used the "See Text" area for what is now designated as a "Marginal Risk".  These did not have colors or outlines, but instead just the words "See Text" on the map.

Note that the "See Text" area actually did have a "hidden" outline, in the tornado\hail\wind risk percentage contours that went in hand with them, as in:

Reasoning for changes:

For the shift from "See Text" to "Marginal", SPC indicated that the trouble was the lack of a precise areal outline.  There were also concerns that the "See Text" area could be overlooked or confusing to the public.

For the implementation of the "Enhanced" designation, SPC asserts that the "Slight Risk" covered too large a range of potential weather.  It definitely is true that "Slight" was by far the most used forecast.  I chose a random month prior to the changeover - July 2014... there were 23 days topping at slight risk, 3 days of moderate risks, and 5 see text days.

There were also slight realignment by weather type, and downward shifts in a couple spots.  The overall changes are summarized in this table of risk criteria:

Old data taken from archive.org

Other Countries:
It's important to note that the US is on the forefront of focus on severe weather and especially tornado forecasting.  Many parts of the world have minimal forecasts.  One key cause of this is that the US averages over 1,000 tornadoes per year, while Canada only about 100, all of Europe about 300, and most of the rest of the world even less (see Wikipedia or this article from ustornadoes.com).

The UK looks like it uses a three color scale of yellow, amber (orange), and red for notices on all weather hazards, which is a combination of how likely the event is with impact table levels of very low, low, medium, and high for how destructive it will be.  It appears that they only issue warnings for thunderstorms, hail, and wind, not for tornadoes directly.  A more straightforward scale... though some concern that the words very low and low suggest a lack of danger... I believe the US avoids these terms for this reason, and instead strays into the words you find more confusing.

Canada appears to only have watches and warnings similar to the basic US versions.

South Africa seems to have a yellow, orange, red scale which is a mix time and intensity.  Yellow can be either up to 5 days in advance, or a lesser weather event in the short term.

A quick look around the met office pages for Australia, France, Argentina, Italy, and Bangladesh show no evidence of clearly defined outlook scales beyond equivalents of watches/warnings.

My familiarity with such sites is incomplete, but the fact that tornado warnings in Australia seem to be a rather notable curiosity, and that the Bangladesh main met office page has a counter suggesting only 160,000 visits highlights that the US may well be in a very unique situation in terms of regular supercellular weather and heightened attention to its threats.  And so detailed scales for such weather may be without comparison.  However, though many other nations certainly have threats to cause great consideration, be it blizzards, tropical cyclones, or sand storms... there doesn't appear to be widespread usage of scales with as many levels as the SPC convective outlook.

Validity:

I believe you're right to question it...

A small study in the dissertation entitled Communicating Natural Hazard Risk: Warnings, Decisions, and Precautionary Behavior by Robert Drost (which likely overlaps the subsequent journal article Severe Weather Warning Communication: Factors Impacting Audience Attention and Retention of Information during Tornado Warnings, which is still unavailable except to subscribers, so I have not read)... found that 37% of the participants were unable to distinguish between a watch and a warning.  (Given that the study is of young college students, this probably greatly underestimates overall misunderstanding in the public... though the use of such a small selective sample means the value could be quite inaccurate in any direction).  If we're struggling with fundamental terminology important to direct life-or-death decisions, changes like these do seem hindering to the public.  I spend a lot time on Facebook tv station livestreams during severe weather, meeting and talking through questions with the public... and in my experience you're right that more people are struggling with the new categories.

There is one perspective that may help offer some understanding and even support the SPC changes; there has always been a loose pattern suggesting that the SPC and other NWS specialized offices aim slightly more at meteorologists and emergency managers than the general public.  This is reflected in the extensive usage of complex terminology throughout the site, the conspicuous citation of journal articles, the presentation of statistics and percentages that really wouldn't have much grounding to the general public, and the rather unadorned pages and overloaded navigation menus that all make it very hard for people unfamiliar with the sites to know where to find what they need.  The new categorization may be quite confusing to the general public, but for an active meteorologist, they were quickly adapted to.

However, the SPC and its brethren at the same time puts a great deal of emphasis on mediums like Twitter and Facebook and does television interviews in key weather events.  So it could reasonably argue that in reality, they are also trying to be public-facing entities.  And in the end they wind up having multiple competing personalities/goals (perhaps true of all of the NWS?)

In the end, the goal of course goes back to prewarning the public.  The SPC may wish the broadcast media can consolidate the messages they put out, perhaps down to just a simpler "there is a chance of tornadoes today".  But the reality is that people clamor for exact values and maps, even at times when they aren't that useful.  And so it typically ends up that the outlook map does make it on to the public (or, more troubling yet, presenters create their own competing scales).  And so we wind up back at the issue that the scale probably confuses the public.

We all know that at some point, information overload is a problem.  And that too many terms will confuse people.

So indeed it may well be after all that the relatively minor severe weather events don't need an outline and term to show it as less than "Slight", but rather just a little hint on the image like "See Text" offered.
And whether or not "Enhanced" helps better warn than confuse people is a very legitimate question.

In the end, the SPC page did note that "the NWS has a strong commitment to engaging the social sciences in evolving our services, and this community has helped inform our decision making for this change."  That's where we must look to.  No studies were published on this change that I know of.  But we have to hope they'll continue to look into it.  Social science is definitely still rather nascent and under-explored in meteorology.  Here's to hoping that greater attention and resources can be dedicated to weighing terms and categories like these.  You've raised a good, helpful point... and one that hopefully filters back to the people making these decisions, encouraging some more firm answers and data.  It's something we definitely need to be thinking about more!


What is the vertical axis of this waveform shown in this tweeted IRIS GIF? This IRIS tweet shows a video of siesmic waves from the recent M6.4 Earthquake in California rolling across the US.

I've made a small GIF to give the idea but the "GIF" in the tweet shows the whole thing.

At the bottom there is a plot of something versus time, the x-axis extends for about 35 minutes!, and the vertical scale bar on the right is 44 nanometers(?) tall.

Question: What does this 1D plot of displacement(?) versus time actually show? Is it a calculated quantity or a direct measurement of something? What are the vertical blue lines labeled P, PcP and Sc5?

  Watch the waves from the M6.4 southern California #earthquake roll across the USArray seismic network (http://www.usarray.org )! #socalearthquake THREAD

Low quality GIF, please see the tweeted original!

Answer 1

The horizontal axis is indeed time (don't forget units and note how long those periods are!). As for the vertical axis, I'm certain that this is displaying vertical (or 'Z' or 'V') displacement. Keep in mind - like you mention - that we are only looking at a 1-D picure of the data, but there are other perspectives we are missing! For example, how is the earth being displaced with respect to North-South and/or East/West directions?

Answer 2

The vertical blue line you reference indicates different seismic phases (or arrivals). For example, you list 'P' and 'PcP' - but there are many others! For example 'SKS', 'SKKS', etc. - see the hyperlink to understand this notation and the seismic waveforms they correspond to.

NOTE(1): For the term phase - be VERY careful with this word and the context I've applied it in. As is customary in geophysics, one word can refer to the same or different concepts. Read here for a good follow-up example of what I'm describing in terms of phase.

NOTE(2): Many seismograms like this will initially be displayed in the conventional NEV (or NEZ) or North-East-Vertical coordinate system . But, to optimize many kinds of analyses and displays, one needs to rotate (or transform) this system into another - LQT. Read here to understand what that means.

NOTE(3): How does one know or estimate seismic phases like these? You need an earth model! From the source location and at the instantaneous moment of when the seismic event occurs, a corresponding seismic wavefield is generated and travels throughout the earth - interacting with its fluid and/or elastic mediums - all the while responding to (or convolving) its complex, 3-D velocity (and density) structure. As the seismic wavefield passes through different mediums via refraction, reflection, dispersion,
attenuation, etc., it changes and subsequent various phases are produced and then recorded at a station. The phases - i.g. 'SKS', 'P', and many others - basically tell a story of how/where the wavefield changed, which is great for analyzing the crust, all sections of the mantle, and even the core!

*I've included a lot here but you've asked an outstanding question that you (and I) can really learn from!


What is the name of the sea in this image? I was reading in Wikipedia about the Indian Ocean and I saw there an image of the part of the globe with a "closed sea" (it's marked by a red arrow in the attached picture). What is the name of this sea?

That's the Caspian sea, considered the largest enclosed inland body of water on Earth by area. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the west, Iran to the south, and Turkmenistan to the southeast.


How to extract lat-lon from MOD10C2 hdf data in matlab? We can import and read all given bands/parameters of MOD10C2, lat and lon is not given as separate band rather embedded with other bands. How we can extract from MOD10C2 hdf data in matlab.

Similar question found here for python

The latitude and longitude of each pixel is not stored in the HDF file. But using

metadata=hdfinfo('file_name.hdf');

You can get the info to generate those latitudes and longitudes. In metadata.Attibutes you will find this among other things:

    GridName="MOD_CMG_Snow_5km"
    XDim=7200
    YDim=3600
    UpperLeftPointMtrs=(-180000000.000000,90000000.000000)
    LowerRightMtrs=(180000000.000000,-90000000.000000)
    Projection=GCTP_GEO

If you rather a more human-readable format, check the product specifications for MOD10C2.

There it say:

  Projection

  MODIS CMG data sets are produced in a Geographic Lat/Lon
  projection. This simple projection treats geographical longitude and
  latitude degrees as if they were x- and y-coordinates in a plane.
  Figure 1 shows the geographical lat/lon projection known as Plate
  Carrée, which plots longitude and latitude degrees as coordinates on
  the x and y axes, respectively:

  Figure 1: Plate Carrée projection.

  Grid

  The MODIS CMG consists of 7200 columns by 3600 rows. Each cell
  has a resolution of 0.05 degrees (approximately 5 km). The upper-left
  corner of the upper-left cell is -180.00 degrees longitude, 90.00
  degrees latitude. The lower-right corner of the lower right cell is
  -180.00 degrees longitude, -90.00 degrees latitude...

With that you have more than enough information to generate the latitude and longitude vectors. Now you have to decide if you will store the center of each pixel, or one of the corners.

Assuming you will store the center of each pixel you can generate the latitude and longitude vectors like this:

gridSize=0.05 % arc degrees
lat=-90+(gridSize/2):0.05:90-(gridSize/2);
lon=-180+(gridSize/2):0.05:180-(gridSize/2);

And if you want instead matrices with the coordinates of the center of each individual pixel, you do

  [lonGrid,latGrid]=meshgrid(lon,lat);


Can we reduce the scale of volcanic eruptions by drilling some canals or bombing some holes in the crater? As we know, when large scale volcanic eruptions occurs, large amounts of ashes and lava rushed out at short time, is it possible to drill some canels or bomb some holes in the crater so that the gas or lava can leak out slower in stead of rushing out quickly and hence reduce the scale of volcanic eruption?

I will be using for an example in this answer the collapse of the lava dome at Mount St Helens in 1980. The lava dome on top of the mountain grew between March 20 and May 18, and then a landslide caused by the angle of the top of the dome exceeding the angle of repose of the country rock caused the pressure on the magma chamber underneath to be released, causing it to instantly boil and explode. Your suggestion to relieve pressure by either drilling or bombing would have had the same effect. Drilling or bombing a hole in this dome would have caused the pressure to greatly reduce, making all of the dissolved gases in the chamber to exsolve out, causing the pressure to instantly greatly increase, over what the surrounding rock was capable of containing.

So by bombing or drilling a magma chamber that might be about to explode, you run the very real risk of guaranteeing that it will explode. The precursors earthquakes to the Mount St Helens eruption would have been the signal that something was wrong you would use to justify this intervention, and as a result you would have simply advanced the timetable of eruption.

A good analogy is that of a radiator cap on a hot car engine. The coolant inside the radiator might be sitting at 20 or 30°C over its boiling temperature, but because it is under higher pressure due to the heat and being pumped around, it has not boiled. Once that pressure is relieved, it will instantly boil out of the radiator because of the reduction in pressure.


Is this a contradiction in Wikipedia's definition of temperate zone? Under the Wikipedia article Temperate climate Temperate climate in the introduction is describes:

  In geography, the temperate or tepid climates of Earth occur in the
  middle latitudes, which span between the tropics and the polar regions
  of Earth.

So by this sentence I take the temperate zone to be between the pink shaded area (the tropics, and the uppermost and lowermost broken lines (arctic and antarctic circles. This is simple enough.

Then in the next paragraph it says:

  The temperate zones (latitudes from 35° to the polar circles at about
  66.5°, north and south) are where the widest seasonal changes occur, with most climates found in it having somewhat balanced influence from
  both the tropics and the poles.

Now it says that the temperate zones are between latitudes about 35 degrees from the equator to the polar circles. This is different than the earlier description, which said it was between the tropics and the polar circles, which is about +- 23.5 degrees to the polar circles, not 35 degrees.

A little lower it says:

  The north temperate zone extends from (approximately 23.5° north) to
  the Arctic Circle (approximately 66.5° north latitude). The south
  temperate zone extends from (approximately 23.5° south) to the
  Antarctic Circle (at approximately 66.5° south). Zones and
  climates

So now it's saying again the temperate zone is between the tropics (23.5 degrees latitude) to the polar circles.

Lower again it specifies that there is a suptropical zone, namely:

  Subtropical climates are generally located between 23.5° and 35° north
  or south on the eastern or leeward sides of landmasses.
  Humid subtropical climates

It's now specifying zones of the subtropics, but it doesn't change the fact that in the first instance it says the the temperate zone is between the tropics, +/- 23.5 degrees, and the polar circles, and then says the temperate zone is between 35 degrees to the polar circles, a definition which excludes the subtropics from the temperate zone.

Which one is correct? Is there a contradiction here? If so, is it a mistake or something more subtle I don't understand?

Note that they say:

  the temperate or tepid climates of Earth occur in the middle latitudes

The word in can be used to convey that the first thing is only a part of the larger second thing... much as, for example, Texas is found IN the United States, or the preteen years are found in childhood.

But by including the additional further explanation of what the middle latitudes are directly after that, I agree it leans a reader towards your interpretation, and is ambiguous and likely confusing to others.

I'll try to make some minor adjustments to the article to hopefully alleviate any confusion.

But in all honesty, it's probably better to not get overly caught up in such excessively precise categorizing.  I tend to believe that what one person, even one climatologist, might call temperate climates may well vary from what another one would classify them.
For example, they can be based on temperature ranges, on prevailing wind patterns, on breaking into equally-sized regions (like Fred commented), etc.

Really, I'd think of the subtropics as sort of a blurry boundary between the tropics and the temperate zone... where the closer you get towards the Equator, the less seasonal variability and frequency of cold air intrusions.

Indeed, even typical places well across into the "official Tropics" can see occasional years with some notable cold fronts, as happened in Cuba and even Costa Rica in the winter of 2010.  So it's not like 23.5 is some magic physical boundary just because that's the northern extent of the sun's latitudinal cycle.

So the Wiki article as you read it appears to be saying the temperate climates are only 35° and 66.5°, only a subsection of the middle latitudes.  But honestly, exactly what you classify the boundaries as is sort of like arguing over which states are in the Midwest or Southern Southern US -- very unnecessary outside of very specific circumstances, and prone to at least occasional dispute probably even among experts.  Yes, a teacher or test may ask you to know their specific definition (whether of temperate boundaries or of which states are in the Midwest)... that's just part of life sometimes.

But the real take-home idea towards understanding how the Earth and specifically climate/weather work is just that there's a Polar region which has very cold polar air basically year-round, a Tropical region which has very warm Tropical air year-round (outside of colder mountains!), and then a "battle ground" that shifts seasonally and even daily in between, altering the weather significantly in those locations.  And local factors like bodies of water and wind regimes can significantly shift regions into a large array of different expected weather


What is a Sand Motor "for"? I've looked at/listened to:

NPR: Protecting The Netherlands' Vulnerable Coasts With A 'Sand Motor'
Zandmotor YouTube: The Sand Motor Five years of Building with Nature
ecoshape.org: Sand Motor Delfland Coast
dezandmotor.nl Introduction
Wikipedia Sand Engine

but I'm still not getting what this is for. Is this a "natural" way to form long-lasting sand dunes on the coast, or something more, or different?

Is it possible to summarize the primary goal of this project? What exactly is the desired outcome, or success criteria?

From the material presented, it appears the southern coast of the Netherlands is subject to coastal erosion which requires the importation of sand to restore the coastal profile and maintain sand dunes that ensure the integrity of the coast.

Previously, sand was imported every five years and deposited along the coast by mechanized equipment, in a series of restoration campaigns. This is a very disruptive process for natural systems and the humans along that part of the coast.

The sand motor is an artificial, sacrificial peninsular of sand that will be redistributed along the coast, continually replenishing the sand lost to erosion. The slower and continuous redistribution of sand, but natural forces will allow for a consolidation of the coastal sand dunes in a seemingly natural manner that is not disruptive like the previous replenishment campaigns conducted every five years.

The continuous slow replenishment of coastal sand, also allows flora to naturally establish itself and colonize the sand dunes. Their roots acting as a mesh to hold sand, thus reinforcing the sand dunes in a natural and non-disruptive manner.

The project is aiming to produce a more natural way to producing long lasting sand dunes to protect the integrity of the coast.


Source of sub-surface ringwoodite water I was reading about the discovery of vast amounts of water locked up in ringwoodite (see here). The authors of the study seem to suggest that previous ideas, involving water deposits being delivered by comets, were brought in to question by the ringwoodite discovery, and that this water was there from the Earth's formation.

Is there no means through which such a large volume of surface water, perhaps delivered by comets, could be subsumed in to the mantle through tectonic processes?

Is there no means through which such a large volume of surface water, perhaps delivered by comets, could be subsumed in to the mantle through tectonic processes?

Definitely. This was happening throughout most of Earth's history, it's happening now, and it will happen in the future.

Subduction occurring in subduction zones are the main mechanism (only mechanism?) of taking stuff from the surface and pushing it down deep into the mantle. Oceanic crust gets hydrated by reacting with the ocean water. Primary magmatic minerals such as pyroxene and olivine are altered into a variety of hydrous minerals: serpentine, amphibole, epidote, chlorite, talc, etc. Once this hydrated crust gets subducted most of the water is volatilised and gets lost to overlying mantle, and even flux-melting it so you end up having volcanoes. Here's a picture:

Source: nature.com

Recent research shows that not all water is lost. Some of it may actually survive the way down deep into the mantle. The identity of the carrier minerals and the exact conditions are still a field of active research and new discoveries are constantly being made. This would most likely form water-rich and water-poor regions in the mantle. The water content of the mantle will thus be quite heterogeneous, which raises the question of how representative was the ringwoodite discovery. After all, it's only one data point.

So to summarise it, yes. Water from the surface can end up in the mantle. This doesn't necessarily mean that this is what is happening, and it may be equally likely that the mantle water is indeed primordial.


How are small mountains created? I understand that large mountain ranges like the Rockies are created by the tectonic plates moving. I live in Arizona and there are a lot of mountains here but from what I understand, there are no plate faults here. How are the small mountain ranges are created?

There are no plate faults in Arizona (actually "plate boundary" is the term that we use - "fault" already has a different meaning, so it could be confusing), but there is still extension of the continental crust. The southern half of Arizona has part of the Basin & Range province, which stretches from Oregon to the south of Mexico.

If you imagine holding a peice of slightly brittle rubber and having someone push up from beneath it, you get cracks in the rubber where it stretches. This is happening to the North American continent. The 'ranges' in "Basin & Range" are the ridges in the rubber, the 'basins' are the cracks. (Exactly why/how this part of North America was pulled apart/pushed up is a subject of intense debate among geologists.)

You can intuitively see how these ranges would not be as high as the Rockies, which formed from a plate of oceanic crust (denser, heavier, thinner) being pulled/pushed underneath the contnental crust (lighter, fluffier, much thicker), causing continental rock to A) bunch up, and B) melt as water is added to it, leading to magma rising and bulging upward into volcanic chains. (Another factor controlling mountain height is erosion, so the Rockies, which are 80 million years old, are lower than the Andes, which are formed a similar way, but which are still being pushed upwards.)

The Himalayas are different again - instead of oceanic crust meeting contnental crust, this was contnental crust meeting more contnental crust, so instead of one side going underneath another, neither side will sink, they're both too light, so they cram into each other creating much higher mountains than either the Rockies or the Andes.

Just doing some quick googling, it sounds like Arizona also has both volcanic feature and eroded remnants of volcanic features. These kinds of mountains/hills are formed via a different method again, and their heights are controlled by their own method of formation. Volcanoes can vary a lot in height. They can be very small, like the volcanoes in south-east Australia where I live, or very large, like the volcanoes in the Andes mountain range, or they can be large, but broad and flat, like Hawai'i.

Erosion can carve out softer rock and leave behind more resistant stuff, and this is how some smaller hills/mountains are formed (like Uluru in central Australia). I found this online which might lead you in some interesting directions: Geologic History of Arizona By Jan C. Rasmussen


What is are the benefits of map 500 hPa geopotential for weather forecasting? From the weather forecasting perspective: what is the main reason for showing just map of 500 hPa geopotential? Are there any practical or theoretical reasons? Why do not show 600 hPa geopotential or 400 hPa instead?
I understand that forecast model usually operates at pressure levels, so this is the reason why choose pressure level instead of quantity at some altitude.

Let us take e.g.:

https://www.ecmwf.int/en/forecasts/charts/catalogue/medium-z500-t850-public?facets=Range,Medium%20(15%20days)&time=2018112900,0,2018112900&projection=classical_europe

The 500 hPa geopotential is usually called the Level of non divergence. It is understood that beneath that level there is a level of convergence and above that level there is a level of divergence so that this surface(500 hPa) is the surface to look for vertical motions. To  a first approximation one can assume the time derivative of density of a particular surface to be a constant and then set the continuity equation to be zero.

$$\nabla. u = 0  $$

We can then expand on the terms on the LHS and separate the horizontal components from the vertical components.

This turns out to be(in isobaric coordinates)

$$ \nabla_H. u_H = -\frac{ \partial \omega}{\partial p}$$

One can then conclude from this equation the following

1) If the LHS is less than zero then there is an increase in vertical velocity with decreasing pressure

2) If the LHS is greater than zero then there is a decrease in vertical velocity with decreasing pressure

Since the atmosphere is bounded at two levels (the surface and tropopause) the vertical velocity is close to zero at these two levels. However in between these two boundaries the vertical velocity starts to increase and achieves it's maximum value before again tapering off at the tropopause. The level of maximum vertical motion is usually the 500 hPa and this is also called the level of non divergence.


Can hippopotamus fossils be found all along the Nile? The image below shows their historical range (red) and current range (green) of hippopotamuses:

Image source: Six Surprising Facts About Hippos, 2014

Hence my question...

Question: Can hippopotamus fossils be found all along the Nile?

Or at least perhaps they used to be found all along the Nile, but now they're all excavated.

They most probably can, but there are two things to be borne in mind. The vast majority of animal corpses never fossilise, as fossilisation requires special conditions. This is especially true of animals from aquatic or very damp environments. Of those that do fossilise, only a tiny proportion are found and excavated.  Some weather out of the rock and crumble away on the surface without ever being noticed by an expert. Many hominid fossils have disappeared in this way.

The other thing required by hippos if they are to flourish and eventually fossilise is a source of vegetable food, sometimes from the river itself, but more usually from grazing on the nearby river bank. Much of the lower Nile today passes through cataracts and deserts, but six or seven thousand years ago the climate was moister, and much of the eastern Sahara was similar to East Africa today, and had similar animals and vegetation. It is quite feasible that in those days there was enough grazing on the banks of the lower Nile to support a population of hippos. They were certainly found in the Nile delta.

There are short stretches that pass through cataracts or strong rapids. It is unlikely that these stretches were ever inhabited by hippos. The current is too strong and food sources difficult to reach, even if they were fairly nearby. Many hippopotamus carcasses are dismembered by crocodiles, which further reduces the likelihood that they will ever be found as fossils. Hippos don't like to stray more than a couple of hundred yards from water, and if there is plenty of aquatic vegetation they will seldom venture onto dry land.


Is global warming being moderated by latent heat of melting polar ice? I've only had a secondary education in physics, so bear with me, but with the greenhouse effect and all, wouldn't we be much hotter already if the ice melt-rate wasn't increasing, since more (heat) energy goes toward changing state, rather than changing temperature? My understanding of latent heat is that it is the applied heat that does not result in a dramatic temperature increase, rather it is used to change state (i.e. solid ice to liquid water).

The obvious issue would be that once the ice is all melted, or it doesn't melt quick enough, we'll have proper heat problems (not just the 2 or 4 or 6 deg changes being discussed now).

Are there numbers available on this? Or is this effect nonsense? Or am I looking towards a time a few orders of magnitude beyond my years?

Latent heat is a factor, but is completely eclipsed by the rate of global warming.

For example, since 1978 the April (maximum) Arctic sea ice has decreased in volume by about $11,000$ cubic km. The latent heat absorbed by the ice to achieve this is about $3.7(10)^{18}$ Joules. Compare this to the amount of excess heat, which has been absorbed by the oceans, which is about $2.0(10)^{23}$ Joules per decade. That is, some three to four orders of magnitude more heat than the decadal heat required to melt the Arctic ice.

Of course there are complications of the heat absorbed by land (much less than in the oceans), melting of Greenland and Antarctic ice sheets, and uncertainty over the depth of oceanic warming, due to sparsity of measurements, especially in the southern hemisphere.

But however you cut the statistics, the latent heat is minuscule compared to the planetary heat imbalance.


What's the difference between these most basic, first-order models for estimating runoff? There are a lot of variations of basic, first-order hydrology models to estimate runoff from rainfall with a few other parameters. From what I can tell, most very basic rainfall-runoff models use one of the following methods at their core: the
SCS Curve Number method, the Rational method, and the Simple method. I'm trying to understand: how do these methods differ, and are there other methods used at the core of basic, first-order hydrology models?

From what I can tell, the SCS Curve Number method is only slightly different from the Rational method in that it uses a Curve Number (based on land use and soils) rather than a Runoff Coefficient (based on soil and basin slope). The two are both event-based models, at least in their initial design.

The Simple method appears to be a lot like the Rational method but the former is for estimating pollutant loading (using pollutant coefficients and runoff) while the latter is for estimating runoff (using runoff coefficients and rainfall). I could see the two being coupled, but they don't appear to have any redundancy in their use.

Considering the summary of my findings, can these methods be described together as "empirical models" given that they are all based on empirically derived coefficients (either Curve Number values, runoff coefficients, or pollutant coefficients)?

The models are similar in that they simplify the rainfall-runoff relationship into a few parameters, and essentially use some kind of first-order coefficient to partition rainfall into infiltration and runoff. The differences are mostly in what other parameters are brought in, such as initial abstraction in the SCS method (i.e. some capture of antecedent moisture conditions). You may wish to pick the method that best captures the information you wish to include in the calculation (or have available), such as drainage area. You can find more details about the implicit assumptiopns and ranges of applicability for each method (e.g. rational method).
In terms of other methods, there are many methods that use some similar forms of soil moisture, soil saturation, etc. to estimate the rainfall-runoff partition. For example, take a look at the Infiltration section (4.2) of the Raven Hydrologic Modelling Framework manual v2.8.
As to whether they are empirical, likely depends who you ask. Empiricism is likely more of a spectrum than a binary system. These are not simply linear regression equations and do capture some physics, although they are still clearly at least partially empirical since the coefficients are basically based on experiments to best fit results. I would likely describe them as empirical or semi-empirical, although I wouldn't spend too much time trying to split hairs for this question.


how much entropy is there in the shape of a rock? If I dig up a given rock, make a 3d model of it, and compare that model with those of a large number of other rocks from the same area, what fraction of other rocks would have the same 3d model?

Let's say that the measurement is performed with an accuracy relative to the size of the rock, so a rock that fits within a 100cm sphere might be measured to within the nearest centimeter.

It would be fine to only look at rocks that have been through similar geological processes, rather than all rocks in an area.

I'm broadly interested in an answer for all land areas on Earth, but if there's data for some small region, or theories about rock shape that allow estimating the average entropy, that would be a useful answer.

This would actually be an interesting research project.  The ability to do a 3-D scan and model of a rock's shape in a manner that is fast enough to get a statistically meaningful number of rocks measured is relatively new.  Certainly you can easily name things that probably control the shape of rocks (lithology, mode of erosion, mode of transport, history of these things) but saying something about this in a quantitative way has not been done AFAIK.

I think this is the sort of question that might result in surprising insights.  Or it might lead nowhere.  Certainly the question 'Does arid region erosion result in different shaped rocks than glacial erosion?'  answered in a quantitative way sounds worthwhile to me.


Can we see the circulation cells in wind maps? Earth famously possesses three distinct circulation cells per hemisphere.

Now out of curiosity one could use a weather app, like windy, to display the wind structures at ground level globally, and the supposed return winds at around 250 hPa height.

When I do that, the picture is very messy and I cannot see any clear circulation cells.

I suppose, that all the other messy physics of the Earths atmosphere will overlap with the cells, but is there a time in the year or variable I can use to see the circulation cells in wind maps?
Or are they in the end just an idealised time-average, that we use to model the winds / (trade winds, famously..) and don't exist at any given time?

Yes, the wind cells are just a toy model, where we can suppose that the homogenity of the Earth and other things. But there are other things and Earth isn't same on the all points, so the instantaneous winds don't follow their cells. Of course, it is possible (by pure statistics) that sometimes in the Earth history, the majority of the winds was aligned with their cells. But the cells are just averaged over the period of more decades and centuries.


Was there once a glacier over Starcke national park in Queensland Australia? I was randomly exploring Google Earth when I came across some sort of rock formation in northern Australia. The location of the rock formation with respect to Australia is shown below. It is in or near Starcke national park.

Of course it seems absurd (to me) to think a glacier could have existed there anytime even remotely recent in geologic history. But there's a rock formation there that looks like it has been carved up by a glacier. Here's a screenshot of google earth satellite data of the rock formation in question:

Notice the clear distinction between the "carved land" and the vegetation to the south and west, this is one of the traits I find confusing about this structure.

I tried researching the park to see if there is a scientifically accepted origin for this formation, but all I learned is that it is apparently made from sandstone, and the region is noted for being very rugged.

I'm not a geologist, so I might be missing some important info that could help, but I have at least a basic understanding of geology from a few electives I've taken in college. I know that glaciers carve up the land, and when they retreat, they leave behind a mess of jagged rocks and lakes that are aligned in the direction of flow of the former glacier. The above picture seems to show just that: there is a clear sense of direction of the lakes and rocks.

Additionally, I was able to find one other similar formation about 400km (~250 miles) north east up the Australian coast (measured as a straight line) near the Sir Charles Hardy Islands. I would show a pic of that as well, but I'm limited because I'm new here.

Other than these two formations, I was unable to find any other examples. Both formations highly contrast their surroundings and both seem to be "smeared" in roughly the same direction.

For reference, look closely at the land in northern Canada and Europe, where glaciers are known to have existed geologically recently. (Again, I had pics but I can't post them.)

Does anyone know how the formation in question was created? If not does anyone have a strong educated guess about what might have caused it? Thanks in advance.

That region forms part of the North Australian Craton and the underlying bedrock is in the order of 1.8 billion years old. The bedrock appears to be overlain by the Isa Superbasin during a period of deposition from 1.575 to 1.665 billion years ago and underwent the Ewamin Orogeny (1550 Ma) to form the Georgetown Inlier.

About 500m years ago the Eastern seaboard of what is now Australia was under water and over the next 250m years continental subduction took place and Eastern Australia was geologically analogous to modern day Japan and China with an inland sea and a volcanic arc stretching from north to south. What was once this inland sea is now part of Australias rich coal basins, which stretch from Collinsville in Quensland all the way to Tasmania and they have also been correlated to coal deposits in Antarctica.

The region you question about, Starcke, is very close to what is known as the Tasman Line, which is a geological separation of the older 1.5 billion year old events and the younger 500 million year old events. The lines in the photo appear to be parallel to where the Tasman Line is shown to be. You'd really need to be on the ground checking out the geology to see how closely your photo images line up with the Tasman Line.

While all this was taking place, there was, amongst other events NE-SW compression of the continental crust along the Tasman Line which may have contributed to the geology in your picture. While I'd take a guess and say that many of those structures are folds (and they look like them too) I'd really need to put my boots on the ground and have a good look before I could say for sure.

Here's a link to an image of The Tasman Line.

http://economicgeology.org/content/97/1/109/F1.large.jpg

A guy called Nick Direen wrote some good papers on the Tasman Line. You might find more info if you google him.

Further to what I've written above, I've looked at the QLD government geological maps online at: https://minesonlinemaps.business.qld.gov.au/

As mentioned by Gordon, the surface geology is comprised of Quaternary age sand dunes which is indicated by the yellow colours. The purple areas are strata that is Devonian age and the small patches of pink are intrusive granites, which are typical of Eastern Australia. The sand dunes overlay the older rocks.

How much the underlying bedrocks influence the sand dunes? Without further research and boots on the ground, I'd have difficulty in saying.


Will a new glacial age take place on Earth or Holocene will become a new climatic epoch? Pleistocene shows a switch between glacial and interglacial ages.

Image source: global-climate-change.org.uk
However, humanity is burning fossil fuels and increasing atmosphere's $\ce{CO2}$ content.

Image source: climatecentral.org
Should we expect a new glacial age after this interglacial or humans will avoid it and Holocene will become a new climatic epoch?

The reason the Holocene began about 12000 years ago was because that was when Northern Hemisphere summers were hot but short. Those hot summers started a melting process.
Right now, July is when the Earth is furthest from the Sun. This makes Northern Hemisphere summers long but mild. That is one of the key conditions that enables a glaciation to start. In particular, glaciations start when summers at high northern latitudes are so mild that all of the snow that accumulated during the previous winter doesn't melt. This triggers a runaway effect by increasing the Earth's albedo. This means the next summer will be even cooler and even more snow and ice will accumulate. Even though we're right about when a glaciation would nominally start, that hasn't happened this time around because of a combination of a lowish eccentricity of the Earth's orbit and a lowish axial tilt (obliquity) of the Earth's orientation, and possibly because of human-generated CO2 concentrations in the atmosphere.
The Earth dodged a glaciation bullet this time around. The next chance for that bullet to hit (aphelion in late June / early July) will be 23 to 26 thousand years from now, and the next one after that, roughly 50 or so thousand years for now. From what I've read, eccentricity and obliquity conditions won't be quite conducive to see the onset of a glaciation the next time around, so the Earth will have to wait 50 or so thousand years to see the possibility of another glaciation.
While that isn't our problem, we can help our children's children's children's children's ... children (about 2000 generations worth) survive that potential glaciation threat 50 or so thousand years from now by leaving them with lots of carbon-containing resources to burn. They might well need those hydrocarbons to prevent a glaciation. As a double bonus, stopping burning those hydrocarbons now will make for a much better life for our current generation of children, for their children's children, and for their children's children's children (which brings us to about 2100).


Technical term for percentage of CO2 remaining in the atmosphere I have a theoretical exercise where I calculated the amount of CO2 that is released to the atmosphere per year (4.6 ppm). We assume that the relative increase of CO2 is 2 ppm, hence the percentage of CO2 that stays in the atmosphere is around 2/4.6 ~ 40 %.

What is the technical term for this percentage?

We call this the airborne fraction, although as the name suggests, it's normally expressed as a fraction rather than a percentage.

Raupach et al (2014) is an (open access) example of it being used in the literature, and in that paper they quote a long-term 1959 to 2012 value of 0.44, so in the same ball-park as your estimate.  Similarly, here's an example of it's use in Chapter 7 of the IPCC AR4 with a range of modelled values from 0.4 to 0.5.  It's also often calculated over single years, as in your example, to look at the trends and variability.

As an aside, the 2 ppm in your calculation is called the atmospheric CO2 growth rate and the total mass of CO2 in the atmosphere would be the atmospheric CO2 burden.


Why is the average 1 Bar temperature on planets with a thick atmosphere proportional to the distance of the sun? The temperature of a planetary body in space varies with the fourth-root of the power incident upon it, this is derived from the Stefan-Boltzmann Law.
This is understandable when applied to a black body in space. However, when applied to certain pressure levels (like 1 bar) at planets with a thick atmosphere the outcome is the same
Meaning that the temperature of Venus at 1atm (Tv) should be the fourth-root of 1.91 times the temperature on Earth at 1atm (Te). Venus receives 1.91 times the solar insolation of Earth.
Venus Tv=∜1.91 x Te
Tv = 1.176 x 288
Tv = 339 Kelvin
For Titan, the temperature of a planetary body in space varies with the fourth-root of the power incident upon it, meaning that the temperature of Titan at 1atm (Tt) should be the fourth-root of 0.01089 times the temperature on Earth at 1atm (Te). Titan receives 0.01089 times the solar insolation of Earth.
Titan Tt=∜0.01089 x Te
Tt = 0.323 x 288
Tt = 93 Kelvin

Planet
Measured Temp 1atm
Relative Solar Insolation
4th Root
Calculated Temp

Earth
~288 Kelvin
1.00
1.000
288 Kelvin

Venus
~340 Kelvin
1.91
1.176
339 Kelvin

Titan
~90 Kelvin
0.01089
0.316
93 Kelvin

I will throw out 2 hypothesises to answer the why of the question. Not saying it is true, just saying that it may be valid hypothesises. And both hypothesises don't discount the internal properties of greenhouse gasses.

Somehow positive and negative feedback forces level each other out in the 1 bar thick atmosphere sytems on all 3 planets

There is another overruling equilibrium mechanism, as proposed by Dr. Ronan Connolly & Dr. Michael Connolly, who studied all the weather balloon data.

https://youtu.be/XfRBr7PEawY?t=2506


Are the precious metals (silver, gold, platinum) present everywhere throughout the Earth's crust at least in the trace quantities? Do some rocks, soils, sands or waters exist that contain fewer than one atom of gold per cubic meter or tonne of their mass?

The average concentration of gold in Earth's crust is about 2 ppb (±0.5, depending who you're asking). This is about 2 milligrams Au per tonne of rock. It's not much, but it still equals about 6×1018 atoms, or 6 billion billion atoms.

Seawater has on average 0.004 ppb of gold. This equals 4 micrograms Au per tonne of seawater. Much less, but still about 1×1016 atoms of gold, or 10 million billion atoms.

So to answer your question:

  ...contain fewer than one atom of gold per cubic meter or tonne of
  their mass

The answer is a clear no.

Edit

These seemingly huge numbers do not mean that there is a lot of gold in the rock. That 0.004 ppb of gold which means 10 million billion atoms, is still only 0.0000000004% of the rock. This is clearly a completely insignificant amount of gold. Nonetheless, this insanely tiny amount of gold still an insanely large amount of atoms of gold. There are a lot of atoms out there.


Why do rivers have 'wells' in mountains? Why/how can rivers have sources in places high above the sea level?

The presence of water underground has nothing to do with sea level in mountainous country.

When rain fails on a mountain, or snow falls on a mountain and the snow eventually melts, the water from the rain or snow melt mostly travels downhill via rivers to the sea.

In getting to a river some of the water will fall on the ground. In places where the ground is covered by soil, water can travel through the soil via the pore spaces between the grains of soil. Similarly if porous rock, such as sandstone lies beneath the soil water can travel through the pores in the rock.

If a layer of impervious rock lies under the porous rock or soil, the water cannot move downwards, due to gravity, any further. This can lead to water accumulating in the soil or porous rock and saturating the soil or rock. In such situations an aquifer can form. The top of the saturated zone in an aquifer is called a water table.

The ground beneath a river is saturated and the surface of the river shows the water table exposed to atmosphere. Thus in mountainous regions the ground beneath rivers will be saturated and capable of supporting a well developed from the bank of a river.


What type of cloud is this? I live in a sub-tropical region of Australia.

Earlier today, we experienced temperatures of 31C and it was clear about 2 hours before I went out and noticed the following clouds directly above my house - the entire sky either has this or is very grey.

There is a constant background of thunder and distant lightning is observed - the wind is picking up a bit, though still a breeze. No rain at this stage.

These are mammatus clouds. The signify instability (via negative buoyancy, convective mixing, entrainment or other sources) at the cloud base which causes the bulbous udder-like structure. As in your case they can often be observed in association with strong convection.


Were there any polar vortexes in 2018? Were there any polar vortexes in 2018? On what dates?

I want to see what the weather looked like on those dates: https://www.youtube.com/watch?v=FPuDPxK88g0

Yes I know. You would think that I could just google it and it would be the first thing on the page. But no.

First of all the question is not appropriately titled. The polar vortex ALWAYS exists as explained in this URL - What is the Polar Vortex ?. The real question is whether a polar vortex split up at the poles and the smaller vortices moved equatorward or not. In February of 2018 the polar vortex did split high up in the atmosphere due to a SSW event.  If we take a look at it from GFS forecast data from the period - February 2nd 2018 10 hPa wind data and then a few days later - February 12th 2018 10 hPa wind data.

Content owned by The National Observatory of Athens, Greece confirms it in this youtube video - Polar Vortex split. An associate of mine who creates popular science videos for the larger public came up with a layperson's view of the polar vortex in this youtube video -SSW explanation plus polar vortex split

The key point in Simon Clark's video of the sudden warming of the stratosphere can be seen in GFS forecast data as well - Air temperature before polar vortex split at 10 hPa and this Air temperature after the polar vortex split
There is a 40 degree centigrade warming of the stratospheric air at 10 hPa over some locations. Over the temporal scale (3-4 days) that is fairly dramatic and that effect is eventually "felt" at the surface level. While the mechanism behind this is still a matter of deep research the impact is synoptic to planetary scale to cause a  cold wave through Europe as was asked in this question - Where did the daily temperature variation go?.

Finally I am not sure of the impact on US stations but I believe it affected Western Canada and Europe.

UPDATE
With NOAA partially restoring their database and their website the images are available now. I am displaying the 10 hPa air temperature for two different dates. One is before the SSW event (9th February 2018) and another one after the SSW event (13th February 2018). The stereographic projection is over the northern hemisphere

As one can make out over large areas of the North Pole the air temperature at the 10 hPa has increased by around 40-50 degree Kelvin and the colder air has been displaced equatorwards. Unlike the GFS forecast images shown earlier these temperature values are the mean values averaged over a single day and are therefore more representative than a single time associated with the GFS data.

Finally the vector wind at the 10 hPa levels on both those two days and you can see clearly the split vortices in this one

Looking at the literature for the polar vortex splits it appears that they also use the geopotential height increase over the poles to indicate the impact of a SSW.
The first image is prior to  a SSW which indicates the presence of a stable polar vortex(lowered geopotential height)

The second image is after a SSW and one that indicates the instability of the polar vortex(it's weakened state) and split vortices over Western Canada and Northern Europe. (Geopotential height increase over the poles).

Copyright Owner for NCAR NOAA images

NOAA NCAR URL


Do lava lakes exist in all volcanoes initially? I know persistent lava lakes are rare, but do they occur in all volcanoes originally, and just not persist over time?

No, they do not.

Lava lakes require the lava to have low viscosity (that is, be very fluid or water like). If you look at the Wikipedia article for Lava lake, you will see that "basalt" or "phonolite" are mentioned. Those are indeed types of lavas (actually rock) that are very fluid. These are the kind of lava that end up forming lava flows.

On the other hand, there are other types of lavas that do not flow, because their viscosity is too high: rhyolite is one example. Explosive volcanoes (think Mt St Helens) are explosive (mostly) because of the high viscosity of the lava. Therefore, volcanoes erupting explosively (almost) never have lava lakes, because the lava itself is not fluid enough to make a lake.


What does this diagram mean? What does the bottom picture represent when it says Lower Emissions (B1) and Higher Emissions (B2)?

The B1 and A2 referenced in the chloropleth maps are referring to the emissions scenarios that were presented alongside the IPCC's Third Assessment Report (TAR) in the Special Report on Emissions Scenarios (SRES). These scenarios referred to the rate, timelines, and total volume of carbon and other greenhouse emissions that might be realized by the end of the 21st century.

These were several scenarios (A2, A1B, B1, etc.) that were used with the aid of climate models to determine what the possible climate change impacts of pursuing "Business as Usual" (A2), to rapidly reducing emissions and stabilizing climate (B1). While some researchers still use these emissions scenarios and the climate models that were presented with them for some predictions, most climate scientists now refer to the more recent Fifth Assessment Report's (AR5) Representative Concentration Pathway Scenarios (RCP).

For more information: http://www.nature.com/nature/journal/v463/n7282/full/nature08823.html


The Geological make-up in my area I live in the Piedmont area of Virginia and only an hour and a half from the foothills of the Blue Ridge Mountains.  I recently found a number of what I believe to be petrified wood specimens.  There is also a lot of quartz in the area.  I am curious about the types of rocks, and other geological formations that may be found in my area.

Your local university likely has a small natural history museum in its geology department. These are generally free and filled with information regarding local geology. I'd start there.....and bring your rocks; the attendant might be able to help you find someone who can identify your rocks.


Sulfate salts of magnesium and sodium What concentrations of magnesium, sodium and sulfate are needed to precipitate solid MgSO4 and Na2SO4 (let's say evaporation is occurring in a system) I'm assuming probably really high because they are soluble salts? But can someone tell me in mg/L how much?

I'm asking because in this paper I read the authors are claiming magnesium and sodium in solution are coming from dissolution of MgSO4 and Na2SO4 but the concentrations are really low... like 20 mg/L of each. If those minerals were present wouldn't concentrations of Mg and Na be much higher?

Solubilities (taken from Wikipedia):

MgSO4: 35.1 g/100 mL (20 °C)
Na2SO4: 13.9 g/100 mL (20 °C)

It does seem that the solubilities should be  an order of magnitude higher than  is quoted in the paper you are reading.

Several ideas:

The paper is wrong.
You did not understand the paper correctly.
The solubilities mentioned above are of the pure compound in pure water. If it's in an evaporite basin the the chemistry of the water might differ and the solubilities might also differ.
As an example, the presence of a more soluble salt will cause the less soluble salt to be come even more soluble (a process called "salting-out"). For instance, if you have an almost saturared solution of NaCl, and you add CaCl2, a more soluble salt, you will start preciptating NaCl once enough CaCl2 is added to the system.
There could be other anions in the system which make Na and Mg less soluble. Borates? Phosphates? Carbonates? Fluorides? The solubility is determined by the least soluble component of the system. Adding sulfate to magnesium silicate isn't going to do much to it in terms of solubility (unless it is sulfuric acid of course).


What is the total mass of organic carbon on Earth? What is the estimated total mass of organic carbon plus elemental carbon (defined here as all carbon in any chemical form, minus carbon dioxide, inorganic carbonates, and other fully oxidized carbon species such as urea and cyanates) in or on the Earth's crust, oceans, surface waters, and atmosphere?

You could never have an estimate which was anything more than a wild guess masquerading as an estimate. To estimate the carbon in living vegetable matter alone would be hard enough, and result in a very inaccurate approximation, but to include the quantity in the Earth's crust as well could only be a wild and very inaccurate guess. The exact quantity of all the Earth's oil reserves, coal, peat, limestone and other carbonates isn't known with any precision, then there are oil shales,tar sands, asphalt lakes,clathrates and God knows what else,but the great thing about a sufficiently large, wild guess is that no one could ever prove you wrong, especially as on a few occasions and by sheer chance, guesses turn out to be right!  But it is an estimate, presumably an accurate one that you asked for, and that is impossible.


How can half a degree of average temperature result in such devastating impact on coral reefs? Yesterday I read a number of news stories about the new IPCC's (International Panel on Climate Change) report regarding the current state of global warming. It reported that we are on track for hitting their safety threshold for global warming, namely an increase of 1.5 °C average temperatures since pre-industrial times. A number of reports are made, such as for example:

Maintaining the goal of 1.5 degrees instead of 2 degrees will result in 10cm lower sea levels by the year 2100.

However it's the report on the effect on coral reefs that really shocked me. At the moment our level is 1 degree above pre-industrial levels. The report predicts that if the level is allowed to rise to 1.5 degrees (which is supposedly going to happen in 2030 at this rate), that 70 to 90 per cent of coral reefs will be destroyed. Further, if this metric rises to 2 degrees, that we can expect over 99% of coral reefs to be destroyed. This pretty much sounds to me that they will all but be destroyed if we allow up to a 2 degree increase.

I'm pretty naive on the subject, so I'm wondering why such a temperature increase of half a degree can have such a marked effect on coral reefs in particular.

Coral die because of coral bleaching, a process in which the symbiotic algae living in the coral (which give the coral its colour), leave the coral host.

Bleaching can occur for a variety of reasons, but the ones that relate to a warming climate are:

Ocean acidification caused by dissolution of carbon dioxide in the water.
Thermal stress. According to this website, "Corals do best when ocean water is between 73 degrees F and 84 degrees F." (22–29 °C). Long durations of heated sea surface water exceeding that would cause bleaching and coral death. For example, a recent bleaching event in the Great Barrier Reef had temperatures of 4 °C above average, where the average is around 27 to 28. This puts it above the comfort zone of the coral.


Average thunderstorm days for each month How can I find the average number of days with thunderstorms for each month for different cities in the United States? I’m doing a researching project for this and I need to find some links that will show me the average number of days with thunderstorms for each month for different cities in the United States.

You should start with NOAA services. They have a Storm Events Database going back to 1950, where you can do queries for states/counties of interest. If you are more interested in lightning data, they also have some products, including raw data from a private company (you'll need access for this) and freely available derived products.


Is there really precipitation on Mars? Does frost count? The NASA Goddard science education page answer to Reading about Mars, I noticed that it has .03% of water vapor in it's atmosphere, and my question was if it has water vapor why doesn't it have precipitation? says

Mars does have precipitation.
[...]However, this precipitation most likely takes the form of frost, rather than rain or snow. The ground is likely to be colder than the air (especially on cold clear nights), and so air hitting the ground cools and the water freezes to the ground as frost. Viking II (a Mars lander in the 1970's) saw frost on the ground some mornings.
A part of the polar ice caps of Mars is made of precipitated water ice (the rest is made of carbon dioxide as 'dry ice').

However another educational page Precipitation (Weather) says:

Precipitation in meteorology refers to all forms of liquid or solid water particles that form in the atmosphere and then fall to the earth's surface. Types of precipitation include hail, sleet, snow, rain, and drizzle. Frost and dew are not classified as precipitation because they form directly on solid surfaces.

Mars has polar ice caps and a 25.19° inclination similar to that of Earth's. We see the polar caps shrink and grow regularly with the seasons each year.
Questions:

Can we say that the changes in the polar ice caps is due to "frost"?
Can we say that the changes in the polar ice caps is due to "precipitation"?
Is there really precipitation on Mars? Does frost count?

See this answer.

Actually already snows on Mars. The snow, made of carbon dioxide, has been observed and studied by orbiting spacecraft. Aside from the different chemical composition from the stuff we shovel on Earth, Martian $\text{CO}_2$ snow also is very finely divided, microscopic in size in fact; likely this is related to the low density of available material and the very fine nature of the dust on which the snowflakes nucleate. In fact studying the snow could provide clues about the atmospheric Martian dust on which it nucleates.

Details are published in the Journal of Geophysical Research.

In addition:

Indirect evidence for water ice snow has also been found. According to an article published in Nature, mixing layers have been identified from orbiting spacecraft and water-ice precipitation signatures have been found by the Phoenix lander. Simulations show that such signatures are consistent with snow formation, with the water-ice snow expected to fall at night (as temperatures cool and the atmosphere can retain less water vapor). The arcticle does not claim any direct detection of water-ice snow."


What is the current theory about the formation of Tibet? Although I basically understand, that how the Himalayas formed, it has always confused me how did the vast high Tibetian Plateau came into existence behind it? And what would be its future, is it expected to remain as such for a long time?

Per yesterday's What-If,

  If you make a building too big, the top part is heavy and it squishes the bottom part.

In the context of Tibet, what this means is that rock has a yield strength: pile it up high enough and it will break (via earthquakes); and if you make a big enough pile, especially of continental material, then the concentrations of radiogenic isotopes will be high enough to significantly raise the temperature - and lower the strength - of the rock in question.

In the case of Tibet and the Himalaya, height increase is due to north-south shortening as the Indian plate impacts the Eurasian plate, i.e. the Tibetan plateau initially formed via exactly the same process as the Himalaya. In order to get an approximately stable height, this increase has to be balanced by decrease. The principle processes causing decrease in height in Tibet are:

east-west extension (see. e.g. Dewey et al. (1988), Tapponnier et al. (1986)), typically along strike-slip faults: this is clearly visible not only in geological maps but also in aerial/satellite photography
erosion rates increase as topography becomes higher, especially in areas of active mountain-building, in part through a change in which erosion processes are favoured

That the Tibetan plateau is of such uniform height corresponds neatly to calculations suggesting that this is the maximum possible height for such features if they are of typical crustal composition.


Can volcanic gases be emitted in any other way besides volcanic eruptions What other sources of volcanic gas emissions can there be on earth?

Volcanic gases are emitted by a number of ways besides eruptions:

Dissolved gases in heated groundwater.

Using a geothermal complex like Yellowstone National Park along Wyoming-Montana border in USA, volcanic gases are emitted through groundwater and water vapor from heated geothermal springs.  One of the most impressive aspects of Yellowstone is that steam rises from everywhere: in parking lot storm drains, potholes, not just from the geysers or springs.
Gas venting from volcanic crater when the volcano is not active.

Gases will vent from volcanic craters between eruption cycles. The emitted gases can be used to determine the level of activity beneath the surface by monitoring volume and chemical composition. Changes in volume and composition can indicate a change in activity up or down.

Often the gases emissions are not visibly noticeable.
Gases can be emitted from a underlying magma chamber through cracks and fissures.

Mount Nyiragongo in Congo has localized carbon dioxide toxicity, known locally as 'mazuku' which are where the gas seeps from the ground in relatively high levels, without the dispersing effects of wind.  This can occur miles from the volcano's summit.

The Great African Rift complex has numerous lakes where CO2 build is a serious concern.
Strongly stratified lakes can trap large amounts of CO2 deep within the lake.
This is evidence that volcanic gases can be emitted across a wide area over a volcanic complex not limited to surface boundaries of a volcano.


How can I create a CF compliant netCDF file? I have been looking for a proper way to create a netCDF file that is compliant with the Climate and Forecast (CF) Metadata Convention. It is amazing that I can find a compliance checker for NetCDF files at the CF-Metadata web page, but I have problems to find any tools or methods to create such a file. How can I create a CF-compliant netCDF file? Are there any good tools, which I can use?

So far this has been the most suitable answer to my question...

NOAA's National Oceanographic Data Center has posted NetCDF Templates v1.0 the CDL templates on their web site. These can be used with netCDF Operator (NCO) commands to create Climate and Forecast (CF) compliant files.

http://www.nodc.noaa.gov/data/formats/netcdf/
http://nco.sourceforge.net/
http://cf-convention.github.io/index.html


Are airliners sensors used to feed weather prediction models? Weather balloons, as well as specially prepared aircrafts, are used to retrieve several atmosphere parameters at different altitudes that are latter used to feed mathematical models for weather prediction.

Nowadays airliners are already fitted with multiples sensors (static pressure, temperature, weather radar,..). Those airliners are flying almost all over the world continuously, and are thus able to provide tons of weather data. In many regions (inside TMA and above) data can be retrieve from ground level to 12000m above mean sea level. Those data won't be as complete as data collected by weather balloons, but can be considered as additional data.
Yet, airliners are operated by private company and exchanging such data can be subjected to commercial contracts.

Are airliners, whose primary mission is not to collect weather data but to transport cargo or passengers, used to retrieve additional data to feed mathematical weather prediction models on a daily basis?

Indeed, airlines are equipped to measure atmospheric data and then put into weather models. The WorldMeteorological Organization's program is called AMDAR. Several articles highlight the impact that the lack of flights have had on the initialization of weather models.

https://www.npr.org/sections/coronavirus-live-updates/2020/04/03/826848818/one-more-coronavirus-problem-accurate-weather-forecasts

https://www.boston25news.com/news/local/covid-19-forecast-how-grounded-flights-are-impacting-weather-forecasting-data/RB7HY6G5ONGE3EHROUKSKT4SB4/

There are a few papers that explore the impact that aircraft data has on initialization:
https://journals.ametsoc.org/doi/full/10.1175/MWR-D-17-0380.1
https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-14-00055.1
https://journals.ametsoc.org/doi/pdf/10.1175/2009WAF2222321.1


How much could Earth's temperature increase by the time we run out of oil reserves? According to this article How long will world's oil reserves last?:

  At the current rate of extraction oil reserves will last 53 years.

And according to this another article, Global temperature - NASA, global temperature increased about a Celsius degree in 80 years.

I suppose we can't directly extrapolate the years because I assume oil's consumption is higher now than before, but is it possible to estimate how much Earth's temperature could increase by the time we run out of oil reserves? Wouldn't it be about a degree or something like happened in the previous 80 years? Is that a problem to really be worried about?

That estimation is based on current extraction rates and based in 2013, so we would have oil reserves until 2066.
Assuming that's correct, it would resemble the "business as usual" future emissions scenario, a.k.a. RCP8.5 (more about RPCs).

According to the last IPCC report, the range of mean global temperature predictions for RCP8.5 looks like this:

We are now 0.5°C above the figure's baseline, and in the next 80 years, which is about year 2100 the temperature would be about 3.5°C above current temperature. But the range spanned by different predictions goes from 3°C to 5.5°C.

Note that the warming effect of putting additional $\text{CO}_2$ in the atmosphere last many centuries, so even if emissions stop suddenly bu year 2066, the planet will keep getting hotter and hotter for a long time.

Also note that the warming is not homogeneous, some areas will warm much more than others, in RCP8.5 scenario many areas would warm by more than 6°C, this animation by NOAA gives you a nice idea of the rate and pattern of warming.

And regarding your question:  Is that a problem to really be worried about? the answer is definitely YES! The RCP8.5 scenario is the most pessimistic one, if that one realizes we will be in a lot of trouble, dealing with climate change, weather extremes, sea level rise and massive migrations.


What is the physical meaning of second moment of wind velocity? I have been reading some documents about meteorological data and many of them mention the second moment of wind velocity.
I guess it has to do with the way the wind is changing but in such case I would call it a gradient... Therefore, what is it's correct physical representation?

The (statistical) variation is not the same as the gradient. The gradient is a measure how things change from here to a nearby point, or from now to a point in the near future. The variation, on the other hand, just says how often wind speeds of different magnitude happen.

For example: If the wind were to blow at exactly 30 km/h all the time, then the average wind velocity is going to be 30 km/h and the variation is zero. Conversely, if the average is 30 km/h and the variation is large, then the wind will blow at different speeds, typically quite different than 30 km/h, but so that the average is 30 km/h.

What's the importance in the context you're considering? If the variation were small, it would be fairly easy to design wind generators because they would only have to accommodate exactly one wind speed, which happens to be blowing all the time. On the other hand, if the variation is large, then you have to design wind generators so that they can produce electricity when there is little wind, when there is the average wind speed, and also when there is a storm. It's a bit like designing aircraft for (slow) take-off and (fast) cruise speeds -- it's complicated, as you can see with all of the flaps and levers moving on the wings of planes between start and cruise phase.


Introductory course on interpreting GOES-R satellite images? As you might be aware, GOES-R is a very rich satellite system that delivers near real-time weather information for the globe. There are at least 16 channels reported (this site is great for monitoring them).
I am looking for an introductory course on satellite image for amateur weather analysis, ideally based on GOES-R. The training offered in GOES-R website seems directed to practitioners. There are some guides around (NOAA site above, for instance, offers a "Quick Guide" for every channel, e.g. Channel 13 but that seems also too advanced for a novice to understand).
Is anyone aware of an introductory course on satellite image interpretation? Naturally, I am looking for an online course, ideally free of charge. If based on GOES-R, the better.

There are numerous short modules offered by UCAR's COMET/METED website: https://www.meted.ucar.edu/training_detail.php
Modules specific to GOES-R include (but aren't limited to):

GOES-R/JPSS test cases for convection initiation and wildfires.
Advanced Baseline imager
A satellite foundational course

There are 19 courses with GOES-R in the title.


Why is the environmental quality index high in USA, the second most polluting country? I saw some indexes about environmental quality in many websites, like in:

http://www.numbeo.com/pollution/rankings_by_country.jsp

I wonder why the environmental quality index is higher in USA and in Europe than in other sub-Saharan or Latin American countries.

We know that approximately 1/3 of the world total pollution is coming from USA and Europe.

It seems to me a little bit strange. Are there any features about the circulation of CO2 on atmosphere that could explain this fact? Or are there just economic reasons that concern development levels of countries?

The website you cited has this explanation:

  Most of our data are based on perceptions (opinions) from visitors of this website. For pollution section, we include some relevant data from World Health Organization and other institutions if we find it helpful.

So basically that index is based on people's perception, and CO2 pollution (which your "1/3 of the world total pollution" is probably based on) is not something that people can see or smell, it's problematic because of indirect effects.

The USA and Europe have pretty strict regulation to reduce the more perceptible components of vehicle and industry exhausts, like soot, sulfur oxides and nitrogen oxides. Their cities also often have good public transportation and zoning laws that separate industry and residential areas.


Are we entering a new Ice Age according to Milankovitch cycles? Milankovitch cycles consist of three orbital parameters: eccentricity, obliquity, and precession of equinoxes.
According to Milutin Milankovitch, the most recent glacial period ended nearly 11,000 years ago, when combination of eccentricity, obliquity, and precession at that time strongly favored deglaciation in the northern high latitudes. Specifically, eccentricity, moving on cycles of 100,000 years, was slightly larger than it is today, and Earth was slightly elliptical than it is today. Obliquity, moving between 22.1 and 24.5 degrees, was nearly at its maximum 11,000 years ago. And precession was pointing at Vega.
It then goes that this combination of orbital parameters enabled the northern hemisphere to experience its summer solstice at the perihelion, which gave the northern hemisphere the largest possible solar radiation on any summer solstice positions. And obliquity was at its maximum, significantly reducing the size of polar regions shielded from solar radiation between the spring and fall equinoxes in the northern hemisphere. So the northern high latitudes experienced a high volume of incoming solar radiation that allowed snow accumulation rate to fall below that of snow melting. Thus, the most recent glacial period started to end.
But now, 11,000 years after the last glacial period, the combination of orbital parameters changed a lot. Eccentricity is near its lowest, making the total solar radiation on Earth at perihelion and aphelion closer than ever. Obliquity is midway between the maximum and the minimum, shielding a significant area of the polar regions from incoming summer sunlight. And precession is now pointing at the Polaris, the exact opposite of Vega. This combination allows the northern hemisphere to experience its summer solstice at the aphelion, and winter solstice at the perihelion, which significantly curtails the amount solar radiation in the northern hemisphere. The northern high latitudes now are shielded more from solar radiation between the spring and fall equinoxes. These new changes seem to make Earth go in the direction of another glacial period, because snow melting seems to be slowing in the northern high latitudes and snow accumulation quickening.
Throughout geological history, Earth has seen far lengthier and more widespread glacials than interglacials. Indeed, interglacials are just short blips in the geological history. It thus seems reasonable to say we are entering another Ice Age according to Milankovitch cycles.

Some of you may cite the current anthropogenic climate change as a rebuttal, but for the question's sake, just ignore it.

It thus seems reasonable to say we are entering another Ice Age according to Milankovitch cycles.

Some of the Milankovitch conditions would appear to make the Earth ripe for a new glacial epoch starting now, or perhaps a few hundred years ago. In particular, aphelion occurs in early July, and obliquity is low. Both of these make for mild northern hemisphere summers, a key condition needed for snowfall from the previous seasons to linger into fall.
But one other key Milankovitch condition needed to make snowfall linger, orbital eccentricity, argues against a new glacial epoch starting now. The low (and decreasing) eccentricity makes the current dip in summertime insolation at high northern latitudes too small of a dip to trigger the onset of an glacial epoch. Look at the graph you posted in your question. Glacial epochs start when summertime insolation at high northern latitudes drops to very low values. The current local minimum is not low enough to enable widespread accumulation of snow and ice over the summer.

Some of you may cite the current anthropogenic climate change as a rebuttal, but for the question's sake, just ignore it.

Even without anthropogenic help, the current interglacial is likely to last for 50,000 years [Berger and Loutre]. With anthropogenic help, the current interglacial may even last indefinitely [Steffen].

Throughout geological history, Earth has seen far lengthier and more widespread glacials than interglacials. Indeed, interglacials are just short blips in the geological history.

That is true only for last 2.58 million years, possibly the last 34 million years. The Earth has been ice-free for most of the last 550 million years. Ice ages (periods during which ice can form, intermittently, are just short blips.

References:
Berger, André, and Marie-France Loutre. "An exceptionally long interglacial ahead?." Science 297.5585 (2002): 1287-1288.

Steffen, Will, et al. "Trajectories of the Earth System in the Anthropocene." Proceedings of the National Academy of Sciences 115.33 (2018): 8252-8259.