User:William M. Connolley/Dynamics of atmospheric circulation

This page has grown out of my looking at Wind and Atmospheric circulation and perhaps a few others - Coriolis effect perhaps. Several of those pages contain overlapping but incomplete descriptions of dynamics. This is an attempt to describe the atmospheric circulation (of the Earth: some concepts, perhaps many, are applicable to other planets but the details vary a lot) from the viewpoint of large-scale dynamics, rather than the names of individual systems.

Don't expect this to progress too fast...

It is possible, and fruitful, to look at the atmospheric circulation as a global heat engine. On average, the equator receives more energy per square metre than the poles, (principally because of geometry, and to a lesser extent because of atmospheric path length and variation of albedo with solar angle). Thus the equator is warmer than the poles. However the temperature difference is modified by polewards heat transport within the atmosphere (and ocean; though atmospheric transport is now thought to be dominant at most latitudes. This article is only about the atmospheric circulation). Thus the poles radiate more heat to space than they receive from the sun and act as the "cooling fins" of the heat engine, to grossly simplify.

On a non-rotating planet warm air would rise at the tropics and sink at the poles, and to close the circulation it would move polewards above the mid-atmospheric level and equatorwards below. And this would be complicated by the convergence of the meridians towards the poles. But that doesn't matter because...

But this simple picture is vastly affected by the rotation of the planet (Coriolis effect).

In the large-scale flow the horizontal component of the wind is always much larger than the vertical.