General Circulation: An Introduction
Here we study the two main 'ingredients' that control the general circulation of the atmosphere:
We focus on both tropical (Hadley) and extra-tropical (eddying) circulation patterns. The Hadley circulation occurs at low latitudes (small rotation) and is axi-symmetric. The extra-tropical circulation (high rotation) is dominated by unsteady, non axi-symmetric motions familiar to us as weather systems. We study both regimes in the laboratory and using atmospheric data.
To set the scene, on the left below we see a view of the earth over the north pole showing
swirling clouds associated with synoptic-scale weather systems. On the right
we show a laboratory analogue of the weather systems in which an ice can
induces a radial temperature gradient in a rotating tank of water. The
presence of eddies in the tank, analogous to atmospheric weather systems, can be seen through the
swirling dye patterns.