Monday, June 15, 2009

Cloud Cover

I was just reading an interesting report on clouds by Willis Eschenbach at Watts Up With That? The post is long and detailed so let me just focus on the conclusions.

1. The sun puts out more than enough energy to totally roast the earth. It is kept from doing so by the clouds reflecting about a third of the sun’s energy back to space. As near as we can tell, this system of cloud formation to limit temperature rises has never failed.
All that is based on thermodynamics. We are not living in a green house. We are living in a huge heat engine.

Point six is pretty good too.
6. The earth’s temperature regulation system is based on the unchanging physics of wind, water, and cloud.
Buh, buh, but, aren't the climate models suppose to be physical? Yes and no. Some physics equations are in there, however when things get really complicated they resort to parameterization. Because who has enough computer power to follow all the zillions of atoms and molecules that make up a cloud? No one. So an algorithm might go like: at temperatures, relative humidity, and pressure between such and such values a cirrus cloud will form and its density will depend on the inputs. All very well and good. But suppose they get it wrong? And suppose that wrong is used millions of times in a 100 year run of the model. And suppose there are 10 other such parameters all interacting. And out of this you purport to tell me what the climate will be like in 100 years? The probability this could all work as advertised is not zero. But it is close enough to zero as to make no practical difference. At least for government work. And isn't all this "CO2 will burn us alive" hoo haa in the main government work? Yes it is.

Cross Posted at Classical Values

1 comment:

tomcpp said...

You could make a much more mathematical convincing argument by saying the only tool we have to predict the weather are differential equations.

Equations that say : if weather pattern X is seen, pattern Y will follow. (Generally people also take into account the surroundings of X, you could think of it as taking a 3x3 square, and using that to decide what happens next in the center square)

Then the earth is divided into little squares, and on every square the calculation is performed. This is then repeated millions and millions of times.

Now this has one obvious result. Every differential equation has the same problem. If the short term prediction of the diff. equation is not absolutely perfect, the long term prediction is utterly worthless.