Our atmosphere is incredibly powerful and is responsible for regulating our planet's temperature.
Due to uneven heating of the Earth’s surface, there is a heat surplus in the tropics and a heat deficit at the poles. The interaction between our atmosphere and the oceans to fill up this gap in the heat content makes our planet a sustainable place to live in.
The way our atmosphere performs this temperature regulation is by building up several giant convection cells. These convection cells are driven by:
The atmospheric cell has two arms:
There are three convection cells in each hemisphere of the Earth:
Between these regions of strong prevailing winds, there are regions of calm air:
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Due to uneven heating of the Earth’s surface, there is a heat surplus in the tropics and a heat deficit at the poles. The interaction between our atmosphere and the oceans to fill up this gap in the heat content makes our planet a sustainable place to live in.
The way our atmosphere performs this temperature regulation is by building up several giant convection cells. These convection cells are driven by:
- Temperature Gradient
- Pressure Gradient
- Coriolis Force (deflects the wind to the right in the Northern Hemisphere and vice versa)
The atmospheric cell has two arms:
- Low Altitude Arm - It blows at the surface of the earth. It is also called the Prevailing Winds as it remains constant on an average throughout the year.
- High Altitude Arm – It constitutes the winds that blow in the high altitude troposphere.
There are three convection cells in each hemisphere of the Earth:
- Hadley Cell (10° - 30°)
When the warm moist air in the tropic rises and moves northwards (towards the pole) it is deflected to the east (in the Northern Hemisphere) due to the Coriolis Effect. At 30° latitude, the air cools down and sinks. It then moves southwest towards the equator to complete the cell. The low altitude arm of the Hadley Cell or the Prevailing Wind blows from the Northeast to the Southwest (in the Northern Hemisphere). They are called the Easterlies or the Trade Winds.
- Farrel Cell (30° – 60°)
Unlike other cells, Farrel Cell is induced by the effect of other cells and behaves like an atmospheric ball bearing. The Prevailing Winds blow from the Southwest to the Northeast and are called the Westerlies.
- Polar Cell (60° – 90°)
When the cold dry air at the pole descends and moves southwards it is deflected to the west. This wind, near to the surface of the earth, is called the Polar Easterlies.
Between these regions of strong prevailing winds, there are regions of calm air:
- Doldrums (or Intertropical Convergence Zone)
The equatorial humid region where warm moist air rises and shreds off its moisture as it cools.
- Horse Latitude
The high pressure boundary between the Hadley and the Farrel Cell at 30° latitude. This is the region where cool dry air descends. The major deserts on our planet lie at this latitude.
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