Tuesday, June 16, 2009

The thermostat of the Earth?

The Thermostat Hypothesis is that tropical clouds and thunderstorms actively regulate the temperature of the earth. This keeps the earth at a equilibrium temperature.

The stability of the earth’s temperature over time has been a long-standing climatological puzzle. The globe has maintained a temperature of ± ~ 3% (including ice ages) for at least the last half a billion years during which we can estimate the temperature. During the Holocene, temperatures have not varied by ±1%. And during the ice ages, the temperature was generally similarly stable as well.

...some scientists have claimed that clouds have a positive feedback. Because of this, the areas where there are more clouds will end up warmer than areas with less clouds. This positive feedback is seen as the reason that clouds and warmth are correlated.

I and others take the opposite view of that correlation. I hold that the clouds are caused by the warmth, not that the warmth is caused by the clouds.

A thunderstorm can do more than just reduce the amount of surface warming. It can actually mechanically cool the surface to below the required initiation temperature. This allows it to actively maintain a fixed temperature in the region surrounding the thunderstorm.

When tropical temperatures are cool, tropical skies clear and the earth rapidly warms. But when the tropics heat up, cumulus and cumulonimbus put a limit on the warming. This system keeps the earth within a fairly narrow band of temperatures.