Global atmospheric circulation Flashcards
What are winds?
Large scale movements caused by differences in air pressure
How do differences in air pressure form?
Differences in temperature between the equator and the poles
What is the pressure at the equator and the poles?
- Equator: low pressure
- Poles: high pressure
Where do winds move from and to?
Winds move from areas of high pressure to areas of low pressure
Define cells (geography)
Global atmospheric circulation loops
What are the 3 cells (from equator to poles) (and latitudes)
- Hadley cell (0-30)
- Ferrel cell (30-60)
- Polar cell (60-90)
What is the weather at high pressure?
Clear and sunny
What is the weather at low pressure?
Cloudy and rainy
What are the pressure belts called (from equator to poles)
- Equatorial low
- Sub-tropical high
- Sub-polar low
- Polar high
What are the winds called in each pressure zone?
60-90 N: Polar easterlies
30-60 N: South westerlies
0-30 N: North East trade winds
0-30 S: South East trade winds
30-60 S: North westerlies
60-90 S: Polar easterlies
Why is the equator warmer?
Sunlight hits the earth most directly at the equator, meaning the sunlight is spread over less area than other places because the earth is curved.
What does hot air do?
Rise
Where does hot air from the equator go?
It rises, cools and moves out to 30 degrees north and south of the equator
What happens when risen air moves to 30 degrees north and south
It cools and sinks, creating a high pressure zone
What are trade winds?
Surface winds blowing air towards the equator
What are westerlies?
Surface winds blowing air towards the poles
Where do trade winds blow from in the north and south hemisphere?
North hemisphere: from the NE
South hemisphere: from the SE
What happens when trade winds meet at the equator?
They get heated and rise to form clouds
What happens at 60 North and South?
The warmer surface winds meet the colder polar winds. The warmer air is less dense than the cold air so it rises, creating low pressure.
What happens to the risen air at 60 North and South?
Some of the air moves back towards the equator and the rest moves towards the poles.
What happens to the air at the poles?
The cool air sinks, creating high pressure. The high pressure air is then drawn back towards the equator as surface winds.
What is the Coriolis effect?
Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.
What does the Coriolis effect cause?
Makes storms swirl clockwise in the Southern hemisphere and counterclockwise in the Northern Hemisphere.
