Tuesday, 19 May 2020

Sunny side up!

From researchgate.net, a diagram showing how the total amount of radiation received at the Earth's surface is more than incoming solar radiation:

Fair enough, this implies that day time temperatures are higher because of The Greenhouse Effect. Seems plausible. If you don't think about it for more than a few seconds.

Problem is, it ignores facts.

Our Moon is the same distance from The Sun as we are. The max daytime temperature is 127C and the night-time low is -173C (from here). That's a day-night range of 300C.  Why is this? It is because our Moon has no atmosphere.

There's no official adjusted average for day-night range on Earth (wildly different for dry deserts and humid cities) but let's go daytime average 20C and average night time 5C? A range of only 15C.

So the actual warming effect of the atmosphere is far stronger at night, when the Earth's surface is 178C* warmer than it would be without an atmosphere (i.e. same as Moon's night-time temperature).

The flip side of this is that the Earth's day-time temperature is 107C* cooler than it would be without an atmosphere (i.e. same as Moon's daytime temperature)- exactly when these  diagrams tell us that the surface should be warmer than it would be without an atmosphere/without The Greenhouse Effect.

Back to the drawing board, lads! Maybe redo those diagrams to explain why The Greenhouse Effect cools the surface of the Earth during the day? (You can't, it's as logically impossible as what the above chart is trying - and clearly failing - to explain).

* Sure, on average the Earth's surface is about 35C warmer than our Moon's surface. That's because we have an atmosphere, full stop, regardless of its constituent gases.


ontheotherhand said...

Very interesting. Thank you. Just one adjustment. "That's a day-night range of 300C. Why is this? It is because our Moon has no atmosphere."

It's surely also because each day on the moon lasts 13.5 earth days?

Mark Wadsworth said...

OTOH, fair point. But all planets and moons with no atmosphere have a very wide day-night range, including Mercury or Mars. The lack of atmosphere is the influence.