Page History

...

where 

Mathinline
body \mathbf{u}_g

 is the speed vector, 

Mathinline
body \alpha

 is the thermal expansivity of the fluid, 

Mathinline
body f

 is the Coriolis parameter, and 

Mathinline
body T

 is temperature. This expression holds only for incompressible fluids, so is valid for the tank experiment: for comressible compressible fluids like the atmosphere we rewrite , the equation can be written in pressure coordinates instead of height.

Convection

The Convection experiment introduces convection as a method of heat transport that helps balance the earth's radiative budget. Since the earth's temperature is roughly constant over time, outgoing thermal radiation must equal incoming solar radiation. The level at which radiation balances turns out to be in the upper atmosphere: below that level, convection acts to transport heat more efficiently than radiation.

Two Regimes in the Atmosphere

The three experiments develop the framework for a model of atmospheric circulation on Earth. The equator-to-pole temperature gradient creates an energy imbalance which is equalized when air moves along pressure gradients and is affected by conservation of angular momentum as it travels meridionally. These constraints produce two structural regimes visible in the atmosphere: the Hadley Cell and mid-latitude eddies.

Hadley Cell

Image Added

Mid-latitude Eddies

General Circulation in the Atmosphere

...

The meridional heat flux consists of two parts: the mean circulation and eddies. The mean circulation is most prominent in the tropics and called Hadley cell circulation, transporting heat from the equator to the sub-tropics. Eddies are the transient heat flux prominent in the mid-latitudes, transferring heat poleward. Together, they transport the heat from the equator to the pole. 

Hadley Cell

We can plot climatological fields showing the meridional mean features of the atmosphere to observe the Hadley cell circulation. There are two phenomena that can be observed in the Hadley cell: the overturning circulation and thermal wind.

...