14
votes
Why is it colder in the mountains than at sea level?
The traditional answer basically comes down to the physics concept of adiabatic cooling, a description of which is:
There is less pressure as you go up in the atmosphere (basically due to less air ...
- 8,713
14
votes
Is spectrum of sunlight the same in the summer as in the winter?
As you suggest, longer the path, larger the proportion of scattered radiation. Since the shorter wavelengths are more strongly affected by the Rayleigh scattering, sunlight appears more red when the ...
- 391
10
votes
What is technically wrong with Wijngaarden & Happer's paper claiming to show that CO2's contribution to surface warming is saturated?
To answer the original question about CO2 saturation, I'll describe spectral absorption. Each gas in the atmosphere absorbs light at specific wavelengths, and some wavelengths are absorbed more than ...
- 101
8
votes
Why is the Earth's shadow blue?
To my eyes, the belt of Venus looks purple, which didn't makes sense to me, as the very short wavelength of purple light should have been scattered long before arriving back there. Then all made sense ...
- 23.2k
8
votes
Accepted
Why does the road appear wet on a sunny day?
This optical illusion is due to refraction of visible light due to density gradients near the surface and the fact that the index of refraction in a medium is dependent on the density of the medium. ...
- 14.1k
7
votes
What would a planet's sky look like with different chemical compositions, such as low nitrogen, high methane etc?
Except for Rayleigh scattering (Is the color of the sky the same everywhere on earth?) gases typically do not add any color to atmospheres, they are usually transparent in visible light. The Halogen ...
- 1,207
7
votes
Are we changing Earth's weather with global warming?
First, regarding your assumptions, here is a graphic from this online textbook.
As you can see, your first assumption is correct, surface radiation is much more significant than thermals. Your ...
- 3,366
7
votes
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Why is the Earth's shadow blue?
How can the air in the Earth's shadow scatter blue light if it doesn't get any direct illumination, and any indirect illumination getting back there should be VERY depleted in blue (i.e. mostly red ...
- 461
7
votes
How much and what kind of radiation passes through a cloud?
Here is not a detailed article, but one you might find some informative thoughts in: http://www.americanscientist.org/issues/pub/sunshine-on-a-cloudy-day
On a basic note, any generalization starting ...
- 626
7
votes
Accepted
How to calculate the solar radiation at any place, any time
Look at the pysolar docs (http://pysolar.readthedocs.io/en/latest/) under "Estimate of clear sky radiation". The algorithm does not return zeros at night, but instead just plugs those ...
- 1,381
6
votes
What is the difference between radiation balance and the global energy balance?
Radiation balance only account for energy transfers trough electromagnetic radiation. Something very useful for the Earth as a whole. As it is the only (or most important by far) way of energy ...
- 17.6k
6
votes
Accepted
What is brown carbon?
Carbonaceous aerosols are formed by a mixture of substances with different chemical, physical, and optical properties.
Certain organic substances are mostly transparent to sunlight and therefore do ...
- 732
6
votes
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Why doesn't earth radiate at wavelengths where there is strong absorption?
Due to the large optical thickness, the outgoing radiation is emitted at stratospheric temperatures (the black-bodies indicated by ~210K temperatures).
Keep in mind that the black-bodies in the graph ...
- 3,152
5
votes
Accepted
How to calculate 3-hour flux values in ERA-Interim?
After my original answer, and some back and forth in the comments, turns out I got the answer right by a bit of fools luck, and we sorted it out...
The thing is, despite flux being commonly thought ...
- 8,713
5
votes
Why are solar longwave and terrestrial shortwave radiations neglected in radiation balance models?
It is because longwave (LW) correspond to a negligible part of the solar radiation and shortwave corresponds to a negligible part of solar radiation.
You can make an experiment yourself using NASA's ...
- 17.6k
5
votes
Effective Temperature of a Planet and Surface Temperature due to Greenhouse Effect
I think you’re not far off with your understanding, but maybe I can put in a few comments to make things clearer.
I often get confused because most diagrams for the Earth energy budget and net ...
- 3,940
5
votes
Solar irradiance/radiation difference
Technically (at least in solar energy industry):
Irradiance is the instant power of solar radiation per unit area, it is measured in W/m2 (it is instantaneous, therefore no time dimension in the ...
- 171
5
votes
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Why is there a window in the absorption spectrum of Earth's atmosphere at a wavelength of 4 μm?
There is simply no strong enough absorption of any of the greenhouse gases at this wavelength. However this does not mean that there is none.
Remember that what you are seeing here is the transmission ...
- 3,152
4
votes
Why doesn't the earth become superheated?
A body has to emit as much thermal energy as it absobs to remain in thermal equilibrium. The Earth has been doing the same since its formation, i.e, it absorbs solar shorwave radiation by its ...
4
votes
What are the major contributors to the amount of infra-red emitted by the earth?
It depends on the wavelength.
The figure shows the most absorbing species between 6 and 16 µm for a U.S. standard tropical atmosphere (Note: this figure does NOT include the Earth's surface!). ...
- 11.6k
4
votes
Why is ozone a greenhouse gas if it absorb UV radiation?
Ozone is indeed a greenhouse gas. But not due to its capacity to absorb/scatter UV radiation, but instead due to its capacity to absorb infrared radiation. In contrast with other greenhouse gases (...
- 17.6k
4
votes
Accepted
Solar irradiance/radiation difference
Solar irradiation is a measure of the energy delivered by the sun per unit area, watts or joules per square metre for example.. It is often recorded over a specific time period, so it is very much to ...
- 4,695
4
votes
How much would 5 gigatons of methane warm the atmosphere compared to 5 gigatons of CO2 if both were released in one go?
In theory, the methane emissions would warm the earth about 25 times more than the carbon dioxide emissions.
That's because of something called the global warming potential. The global warming ...
- 41
4
votes
Interpretation of Mie scattering
Based on the comments and after a lot of trial and error plus reading carefully the Miepython documentation (!), I managed to answer my question:
For the problem that I wasn't able to reproduce ...
- 201
3
votes
What are the major contributors to the amount of infra-red emitted by the earth?
What is most mysterious to me, what is the 'factor' of infra-red production by different surface materials.
In asking about different surface materials, you are missing the big picture. If you want ...
- 23.2k
3
votes
Are we changing Earth's weather with global warming?
I think the short answer to your question is "yes". Getting into the specifics though, it's a lot more complicated.
I can't speak to the specific RF and atmospheric interactions, but the changes to ...
- 572
3
votes
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What are the major contributors to the amount of infra-red emitted by the earth?
Q: What radiates energy back into space?
A: anything above absolute zero temperature. That is, absolutely everything, according to the Stephan-Boltzman's law:
$$W = \sigma T^4$$
Where $\sigma$ is ...
- 14.2k
3
votes
Accepted
What causes aurorae?
When the solar wind is funneled into the Earth's magnetic poles, those particles excite the electrons of molecules in the atmosphere which then bumps those electrons up into another orbital. When the ...
- 2,177
3
votes
Accepted
What is radiation divergence?
The way I understand it, the net longwave radiation $L^\star:=L^\downarrow-L^\uparrow$ (maybe with different sign), i.e. the difference between downwelling and upwelling radiation, can be viewed as a ...
- 994
3
votes
Accepted
Why is ozone a greenhouse gas if it absorb UV radiation?
Tropospheric (near the surface) ozone is a powerful greenhouse gas, even in trace amounts. Strataspheric ozone or the ozone layer is opaque to UV rays coming in and it's opaque to IR rays going out ...
- 5,847
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