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Comment by zamalek | Hacker News Reader

I had never noticed just how much cloud-cover there is globally. Wondering if it was just an artifact if the false coloring, I did a search. Turns out that that level of cloud-cover is normal[1]. Fascinating.

[1]: https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD...

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One of the primary science justifications for DSCOVR is its ability to measure the total combined reflectivity of Earth, dynamic cloud cover and all.

This albedo as it’s called is very important for climate science, and opposition to what climate science tells us about the world was an important part of the Bush administration deciding to not actually launch the finished satellite (the main reason being the overall idea was by Al Gore)[1]

All this is to say: check out these real images of the entire Earth https://epic.gsfc.nasa.gov/

[1]: https://www.airspacemag.com/space/al-gores-satellite-1809521...

> albedo

That's exactly why I found this so fascinating. I know that the ice caps are extremely important for slowing climate change (due to their albedo, being completely white). I had no idea that clouds were so prevalent. My initial thoughts on seeing that image were "wow, that's a lot of albedo, has climate change improved cloud coverage?" A directly counteracting force to the most dangerous GHG (water vapor). Turns out maybe not? We don't have industrial age data in this, so we can't tell for certain - but maybe (likely not) there is a glimmer of hope.

Thanks for the additional information, either way.

Clouds work both ways: They reflect short-wave visible radiation back into space, but they also send long-wave thermal radiation back to the ground and keep it warmer (compare your experience with cloudless nights to ones with clouds).

So far it looks like high clouds have a cooling effect and low clouds have a warming effect. We are not sure yet which clouds will increase more (this may not be up-to-date or might be known soon) but we expect more clouds in general in a warmer climate.

You have it backwards; the cirriform clouds are mostly transparent to visible but absorb and re-emit IR effectively (cloud greenhouse effect). Low clouds tend to have a very high albedo, hence effectively reflect incoming solar radiation, like ice/snow.

Indeed, thanks for the correction!

A lot of the global images of clouds (like this one [1]) are actually made from infra-red images, as making a visible composite is difficult. This means that they can only see high, cold clouds, so you only really see storms.

For example, the GOES-17 image shows large amounts of cloud off the western coast of South America. This is completely missing in the composite video, as it is very close to the surface and so almost invisible in the IR (it is close to the same temperature as the surface). About 2/3 of the globe is cloud covered on average [2].

[1] - https://www.youtube.com/watch?v=4wLYHyCiIyQ

[2] - https://www.atmos-chem-phys.net/10/7197/2010/acp-10-7197-201...

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