Question

Draw a simplified diagram to show the general circulation of the atmosphere over the globe. What are the possible reasons for the formation of subtropical high pressure over 30° N and S latitudes?

Answer 1

The general circulation of the atmosphere also sets in motion the ocean water circulation which influences the earth’s climate. The general circulation of the atmosphere also affects the oceans. The large-scale winds of the atmosphere initiate large and slow-moving currents of the ocean, which in turn provide input of energy and water vapour into the air.

These interactions take place rather slowly over a large part of the ocean. The air at the Inter-Tropical Convergence Zone (ITCZ) rises because of convection caused by high insolation and low pressure is created. The winds from the tropics converge at this low-pressure zone. The converged air rises along with the convective cell. It reaches the top of the troposphere up to an altitude of 14 km. and moves towards the poles. This causes accumulation of air at about 30° N and S. Part of the accumulated air sinks to the ground and forms a subtropical high. Another reason. for sinking is the cooling of air when it reaches 30° N and S latitudes.

Simplified general circulation of the atmosphere