1.1.2 Circulation Cells

Question 1

What are Global Atmospheric Circulation Model?

Answer 1

The global atmospheric circulation model describes how air circulates between low and high-pressure belts as a result of differing conditions at different latitudes. This involves the transfer of heat via circulation cells.

Question 2

What happens at the equator?

Answer 2

• The Earth’s surface is warmed by the Sun at the equator. The Earth transmits this heat to the nearby air. This air gets hotter and rises. The rising, hot air forms a low-pressure belt. As the hot air rises, the air will begin to cool, with water vapour condensing, creating rain and clouds.
• The rising air cools and moves away from the equator towards 30° north and 30° south.

Question 3

What happens at 30° north and south?

Answer 3

• At 30° north and south, the air is further from the equator and the cool air falls. This results in a high-pressure belt with minimal rainfall and no clouds.
• When the cool air reaches the Earth’s surface, surface winds blow the cool air either towards the equator, or away from the equator towards the Poles.

Question 4

What happens at 60° north and south?

Answer 4

• At 60° north and south, cold air blown from the poles meets warm air surface winds. Because the warmer air is less dense, it rises and forms a low-pressure belt.
• The air splits, with some returning back towards the equator and the rest heading to the poles.

Question 5

What happens at the poles?

Answer 5

• At the North Pole and the South Pole, cool air will sink, forming a high-pressure belt.
• This high-pressure belt will move back towards the Earth’s equator as a surface wind.