Tricellular Meridional Circulation of the Atmosphere | Geography Optional for UPSC (Notes) PDF Download

A three cell model of meridional atmospheric circulation, also known as tricellular meridional atmospheric circulation, in which it is assumed that there is cellular air circulation at each meridian (longitude). The global air circulation can be divided into three cells according to this model. The temperature and kinetic parameters involved with global air circulation have been used to divide these cells. 

Atmospheric Circulation

Atmospheric circulation is the large-scale movement of air that, along with ocean circulation, is used to redistribute thermal energy throughout the Earth's surface.

Tricellular Atmospheric Model

• The meridional circulation of the atmosphere is explained by the tricellular model.
• The global air circulation can be divided into three cells according to this model.
• The temperature and kinetic parameters involved with global air circulation have been used to divide these cells.

Hadley cell

• In both hemispheres, the cell is found between 10 and 30 degrees latitude.
• This is a solar cell that has been thermally induced as a result of high solar insolation.
• Along the equator, rising air is caused by high insolation.
• The ascending air cools below the tropopause and forms the anti-trade wind, which blows away from the pole.
• They lead to upper air about 30 degrees latitude, which sinks and causes subtropical high pressure.
• This cell is completed by the trade wind, which travels from the High Pressure toward the equator.
• It's one of the most stable cells, and it's linked to a tropical monsoon and a desert climate.

Ferrel Cell

• In both hemispheres, this cell stretches from 35 to 60 degrees latitude.
• This is a dynamically generated cell that is thermally indirect.
• Warm air may be seen ascending from the polar front and breaking through near the tropopause in this cell.
• The polar front is more continuous in the middle troposphere, which is the most notable aspect of this cell.
• The tropical and polar front dells both contribute to air subsidence at the horse latitude.
• The westerly wind blowing toward the poleward side completes the circulation on the surface.

Polar cell

• In both hemispheres, it stretches from 65 to 90 degrees.
• This is a thermally direct cell that is at its most powerful in the winter.
• As the easterly wind travels towards the subpolar low, sinking air moves along the poles.
• The easterly and westerly winds collide at the subpolar lows, causing the air to rise and complete the polar cell circulation.

Significance

• It aids in the formation of doldrums, or the inter-tropical Convergence Zone (ITCZ), the world's most important and continuous belt of convergence.
• The Hadley cell's air circulation manifests itself in the world's tropical deserts.
• The upper air circulation and the trade wind movement have a significant impact on the monsoon phenomenon.

Conclusion

Meridional circulation is also responsible for the formation of tropical cyclones, temperate cyclones, and anticyclones. Above all, it is crucial to comprehend the global climate. Thus meridional circulation not only is an important phenomenon on our planet earth but also in the UPSC Examination.