38 votes

Antarctic and arctic meltwater is "bad" because it's dark, but why is transparent liquid on white stuff so dark?

Water has lowest EM absorption in the blue part of light spectrum and increases rapidly towards both UV and red parts of spectrum. As a result in visible light water is blue. Same goes for the ice ...
NotAName's user avatar
  • 689
17 votes

Antarctic and arctic meltwater is "bad" because it's dark, but why is transparent liquid on white stuff so dark?

"Transparent" is not the same as "white" : white bodies reflect most of the light while transparent bodies let the light though. Once the light enters into water, it may need to travel a long way ...
Dmitry Grigoryev's user avatar
12 votes

Why are the clouds white and Australia black in weather satellite infrared images?

I had a very similar question in a job interview! The only difference is that it was an image from SEVIRI on Meteosat. The imager on HIMAWARI is called the Advanced Himawari Imager (AHI). The AHI ...
gerrit's user avatar
  • 11.6k
11 votes

Why are the clouds white and Australia black in weather satellite infrared images?

It is likely because there is already a conversion from the raw data to the grayscale image posted on the CWB website. From this online course (emphasis mine): [...] using the mathematics behind ...
Jean-Marie Prival's user avatar
5 votes

Is there a formula that gives the temperature of an object or person exposed to the sun?

It is not an easy problem even for a simple object. The temperature will vary as the conditions change, but the usual approach to such problems is to find the equilibrium temperature for a set of ...
Camilo Rada's user avatar
  • 17.6k
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 ...
Charles Tucker 3's user avatar
4 votes

Connection between radiative imbalance and radiative forcing

That +2.2 W/m2 is the effective radiative forcing, which is the difference in net top of atmosphere radiation in response to a changed set of conditions (e.g., greenhouse gas and aerosol ...
Deditos's user avatar
  • 3,940
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!). ...
gerrit's user avatar
  • 11.6k
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 ...
Gemechu Fanta Garuma's user avatar
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 ...
David Hammen's user avatar
  • 23.2k
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 ...
Gordon Stanger's user avatar
3 votes

Antarctic and arctic meltwater is "bad" because it's dark, but why is transparent liquid on white stuff so dark?

Water (solid or liquid) has some absorbtion. It is rather low for pure water for visible or near-visible light and that's why water it is considered transparent. But only to an extent - few meters of ...
fraxinus's user avatar
  • 571
2 votes

How does a volcanic eruption cool the planet's surface?

What I'm interested in is how exactly this cooling happens. Which is correct: the atmosphere is experiencing a deficit of input energy, or the surface is experiencing a deficit of input energy, which ...
David Hammen's user avatar
  • 23.2k
2 votes

Modified blackbody model of earth. What is wrong with it?

The premise that the Stefan-Boltzmann equation is used for greenhouse gases is wrong. The Stefan-Boltzmann equation is used for irradiance output, not energy input. The ground warms the atmosphere, ...
BarocliniCplusplus's user avatar
2 votes

How does Earth's thermal radiation into space vary by location and time of day?

The yearly average Top Of Atmosphere (TOA) Outgoing Longwave Radiation (OLR) is around 145–345 W/m², as measured by the AIRS instrument: Source: Wikimedia Commons contributors, "File:AIRS OLR.png," ...
gerrit's user avatar
  • 11.6k
2 votes
Accepted

Why doesn't the earth become superheated?

The hotter the Earth gets the more it re-radiates energy back into space.You can see a tiny fraction of this energy by looking at the new moon. The feint glow is just a small part of the re-radiated ...
Gordon Stanger's user avatar

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