Caption: Atmospheric circulation of Earth's atmosphere displaying the Hadley cells, the Ferrell cells and the polar vortices.

Features:

1. The atmospheric circulation cells are giant convection cells caused by the differential heating of the Earth by the Sun organized into bands by Earth's rotation.

2. The convection is between the relatively hot daytime and tropics and the relatively cold nighttime and polar regions.

   The temperature difference between these two pairs of regions is sufficient for convective instability.

   The convection keeps the temperature difference from being larger than it is.

3. In a very general sense, the Earth atmospheric circulation is like gas giant band structure. They both arise from the combination of atmospheric convection and planetary rotation. But there are vast differences in detail.

4. Probably the main reason why Earth has weather that varies strongly from its sort-of average (which is climate) is convection which is turbulent and chaotic to some degree.

   Obviously, the atmospheric circulation has an average behavior, but small deviations can chaotically grow into relatively large deviations that we call weather.