Wednesday, February 8, 2017

A Finite Amount of Water Vapour - Part 1

What is the acknowledged El Supremo greenhouse gas?  Water vapour.  But it doesn't act as a sheet of glass, stopping convection, it has wild convection.  It acts an insulator for the Earth's heat.  Without water, we'd be a dry dusty desert, horribly hot during the day, and perhaps -40 at night.

That's what saves us.  The ocean desperately tries to shed heat to outer space, but it can't do so without a lot of water vapour.  This condenses as rain, and falls back down.  The heat capacity (specific heat) of water is 4,000 times that of air (by volume).  There is a little heat shed above the clouds, but not much, as witnessed by smooth flights over regular rain clouds.

It's amazing that if condensing clouds were all over the world, we'd be in the Jurassic.  But we have limited water vapour.

The heavy colours are condensing clouds.  Only a thin band at the equator. All the water for us living at the extremes comes from air plumes branching off from this band.  The warm water of the ocean is always trying to pump out more vapour, but the darn stuff keeps coming back.  There has to be a way to get more vapour out and cover the Earth.

This is the classic water cycle.  It's the boring story I told all the kids to get them to sleep at the cottage.  They still talk about it!  But this picture is missing a huge amount of water.  Those new to boring stories might not know, but you'll have to wait for the next episode.

-to be continued

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