Sunday, November 10, 2019

Ice Age Physics -- Part 3

Let's pretend we can do a physics experiment at home.  You actually need a full atmospheric physics chamber, which nasa had, before they burned it down with all the books and people on stakes.

This pertains to the maximum that you can heat water with radiation.  There are three types of heat energy transfer -- conduction, convection and radiation.  You boil your pot on the stove with conduction, and the heat gets transfered within the water by convection.  You can feel the heat looking at it, with your infra-red receptors, and that's radiation.  At sea-level pressures, you cannot get the temperature of the water above 100 C.  That is one of our wonderful physics constants.

For the experiment you are heating an insulated bucket of water with a powerful light.  What is the maximum temperature.?  It isn't 100 C because the steam will so thick you can't see anything, and water vapour (condensed or not) is the most powerful radiation blocker on the planet, probably 1000 times greater than any gas.

Since your light is a mythical white laser, you can be quite far away and put the full sunlight heat flux on the water.  Evaporation both cools the water, and blocks the light (exponential feed-back!).  What is the temperature?  Move the light farther away, and cool the ambient (air) temperature to that of 1000 feet above the sea.  Now what is the temperature?

I don't have a clue, but it turns out that in the real world, on the real equatorial ocean, the answer is 30C.  There is no physical law for this, it is just observed.  Weird, confined conditions can above this a little (just for the persnickity).  This is a real-world constraint.  The mechanism could be looked at closer, but it seems that there is wild convection at about this temperature, both in the water, and in the air.  Lots of rain, atmospheric plumes, typhoons and hurricanes.  As well as ocean currents branching away from the equatorial band.

At this temperature, amazing things happen.  If there is a hurricane, the extremely low air pressures in the middle practically cause the ocean to boil (not really, but evaporation goes up an order of magnitude).  They should measure that.  Suffice to say that after a hurricane passes you can see a significant drop in sea temperature.

There's a lot of physics here, and the carboneers get it all wrong.  They can say it was all done in 1850 -- Ha!

-- to be continued

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