Question

Describe the formation of the temperature bands that exist on the Earth and the way in which those temperature bands form the air currents over the Earth.

Answer 1

There are five major bands of temperature or we can say in broad terms as Climate-types on Earth. This are mainly due to duration of exposure of these areas to Sun. Areas where Sun's rays go straight are found to be more hotter areas than the poles of the Earth, where sunlight reaches for very less time.

The movement of air currents are governed by various factors, most prominent is pressure gradient generated due to fluctuations in temperature of the land's or water surface. Air above the land or water surface is affected by the respective temperatures of those areas. Warm air tends to be lighter and raise up and cold air takes its place. This creates a pressure gradient and we refer them to as air currents or even winds at some point. Air currents are also influenced by Earth's rotation.

Air masses and Fronts Polar ir Sub-polar low Sub-tropical high Tropical Air ITCZ Tropical Air Sub-tropical high Polar Air Sub-polar low

The above figure shows movement of air curents on the earth. These are majorly affected by the heat transfer taking place at the huge masses of oceans. Sunlight is direct to them, so they absorb more heat and release, creating drastic pressure gradient above their surfaces. Below is another image showing more clear movement of air. Blue arrows represent cold air and red as hotter.

Single cell atmospheric circulation Tropics: Convergence In the lower atmosphere Divergence In the upper atmosphere Surface winds blow from the poles to the equator