Global Atmospheric Circulation Flashcards
Describe the process of global atmospheric circulation.
The Earth’s surface receives insolation at the equator.
This heats up the air, causing it to rise - creating a low-pressure belt.
With height, the air cools and moves 30 degrees N/S due to the Earth’s rotation.
At 30 degrees N/S, the air cools and sinks - creating a high-pressure belt.
The sinking air either moves back towards the equator or towards the poles due to surface winds.
At 60 degrees N/S the warmer surface winds meet with polar winds - as the surface winds are less dense, they rise to form a low-pressure belt.
The air splits - some moving towards the poles and some back towards the equator.
Describe the climate zones in the Hadley cell.
Along the equator the angle of receipt of insolation is at right angles, which concentrates the heat. This means warm air rises, but with height it cools and condenses to form convectional rain, leading to a hot and wet tropical climate ( such as tropical rainforests).
Due to the spin of the planet, this rising air at the equator spreads and with height cools, becomes denser and so is forced to sink.
This sinking limb of denser air means rainfall cannot form which creates an arid climate between 30-40*N/S ( such as hot deserts ).
Describe the climate zones in the Ferrel and Polar cell.
At the poles the angle of receipt of insolation is low which spreads the heat, and orbit around the sun means no insolation is received for 2-3 months.
This means cold air sinks leading to high pressure, which means little rain ; creating a cold desert polar climate.
The pressure gradient between the poles (high pressure) and the equator (low pressure) means wind travels from high to low.
This colder air meets warmer air at 50-60*N/S which forces the air to rise at the polar front.
This creates the rising limb of the Ferrel cell and creates a temperate climate characterised by frontal rain and wind ( such as temperate woodlands).
