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 ...
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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 ...
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  • 391
11 votes
Accepted

What atmospheric radiative effects, if any, do contrails cause?

We had a surprising opportunity to study this very question during the period of September 11-14, 2001, when all air traffic was grounded across the United States. The research was inconclusive, but ...
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  • 2,688
9 votes

Equation for solar radiation at a given latitude?

Ignoring meteorological factors and any dust or satellites, this is still an incomplete problem. You would also need to know the rotation axis. For example, Uranus rotates completely on its side (i.e. ...
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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 ...
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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 ...
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  • 3,294
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 ...
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  • 626
7 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. ...
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  • 13.9k
7 votes
Accepted

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 ...
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  • 406
6 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 ...
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  • 1,157
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 ...
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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 ...
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5 votes

What is the ratio of infra-red light absorbed by green house gases?

There is no simple relationship since it all depends on the frequency (IR spectral lines for most species of molecules are a mess). The most direct and precise way of calculation is through line-by-...
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  • 2,083
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 ...
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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 ...
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5 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 ...
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  • 1,361
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 ...
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  • 3,133
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 ...
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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!). ...
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  • 11.1k
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 (...
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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 ...
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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 ...
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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 ...
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3 votes
Accepted

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 ...
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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 ...
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  • 2,137
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 ...
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  • 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 ...
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  • 5,667
3 votes
Accepted

How to derive the total potential energy of the atmosphere?

First, let's acknowledge this fact: $$c_p=R+c_v \tag{1}$$, where $R$ is the specific gas constant. This means that $x=R/c_p$. Rearranging the equation, we can see that $$P+I=\int{c_p\left(\frac{P}{P_{...
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