Naked Science Forum
Life Sciences => The Environment => Topic started by: dalniente on 26/07/2019 23:17:22
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Purely hypothetical question, of course. If sunlight was cut off from earth--say, if earth as it exists today was trapped within an opaque bubble in medium earth orbit so none of the sun's light or heat or radiation could get through--how long would we have before precipitation stops?
After the water on Earth's surface freezes, I assume the remaining water vapor in the air will condense, precipitate, and fail to evaporate, thus ending the water cycle (yes?). But I'm curious about the timing. I've found some blog posts and articles that address similar hypotheticals, and most do talk about what happens to earth in a the first year...but from a very broad viewpoint. I love nitty-gritty details! But I lack the know-how to calculate this for myself. Can anyone help?
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Would this bubble allow our heat out?
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Would this bubble allow our heat out?
Oh, good question. I imagined it would be pretty high above the atmosphere, so I just assumed heat would still escape into the space between us and the bubble.
For simplicity's sake, let's say yes, it would allow Earth's heat to escape.
Thanks!
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I imagined it would be pretty high above the atmosphere
Let's assume that this insulating bubble was 10x farther than the Moon....
The mass inside that volume currently has a black-body temperature of about -15C, and the greenhouse effect keeps the Earth's average temperature slightly on the positive side of the Celsius scale.
The thermal radiation from the Earth would bounce back about 20 seconds later, warming the Earth and Moon uniformly.
The Earth and Moon's average temperature would not change much, but it would even-out around the globe.
This would cause melting of ice-sheets, which would absorb a lot of heat, and cause rapid sea-level rise.
I am guessing it would take a few months for the Earth's average temperature to drop below 0C - and even then, a few areas like Iceland and Yellowstone would have ice-free pockets.
If, however, the Sun disappeared, and the Earth could radiate heat into the black of space, I expect that most areas would go below 0C within a week, although freshwater lakes would still have liquid water under the layer of ice (at least, for a while longer).
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Nice post. Thanks a lot.
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The current water cycle would pretty much stop instantaneously, the water would precipitate from the skies in the same manner that rain happens at night more than at daytime. The miniscule water vapour would not be replaced as the earth would be cool.
A new water cycle would begin, the oceans would not be warmed anymore, the thermal content of the oceans not being much above freezing, the air being very cool now all causing the oceans to continue only small scale evapouration cooliing until the oceans froze.
Then a new water cycle would continue until the atmosphere contracted to the point of being sustained by the earths own interior heat.
The time for the oceans to freeze at the surface would probably be best estimated by looking at antarticca or the north pole. Even with just the sun blocked at the pole increace is fairly rapid, with the whole earth in shadow, yet the earth still warmish, a couple of years should be more than enough for total solid ice, probably a bit faster.