Evaluate the Role That the Tri-Cellular Model of Atmospheric Circulation has in Dictating Global Climate
Evaluate the Role That the Tri-Cellular Model of Atmospheric Circulation has in Dictating Global Climate
The Tri-Cellular Model of Atmospheric Circulation shows how energy is redistributed across the globe and ensures there is not a surplus at the equator and deficit at the poles, which would be caused by the differential heating of the Earth’s surface by the Sun. The tri-cellular model is made up of three different air masses which control atmospheric movements and the redistribution of heat energy. The three air masses, starting from the equator, are called the Hadley cell, Ferrel cell and the polar cell.
Between the two Hadley Cells is an area of low pressure in equatorial latitudes known as the inter-tropical convergence zone (ITCZ). Here, at the equator, the sun is always high in the sky so this area receives a large amount of solar insolation so the ground heats rapidly in the day and there is a lot of surface evaporation and the air becomes extremely humid. As the hot air rises in convection currents an area of low pressure develops. This rising air cools and water vapour eventually condenses into cumuliform clouds and heavy rainfall results. Weather stations in the equatorial region record precipitation up to 200 days each year, making the equatorial and ITC zones the wettest on the planet. The equatorial region lacks a dry season and is constantly hot and humid but because the climate that has both rain and sun means that these areas are able to host one of the most diverse ecosystems on the planet in the form of rainforests. The Inter-Tropical Convergence Zone acts as a conveyor belt for hot, humid air that turns water vapour from higher latitudes into rainfall near the equator.