Global Atmospheric Circulation Flashcards
what are winds
large scale movements of air caused by differences in air pressure
what are differences in air pressure caused by
the differences in temperature between the equator and the poles
where do winds move from and to
- winds move from the areas of high pressure
- to the areas of low pressure
what are winds a part of
they are a part of the global atmospheric circulation of loops or cells
- these loops have warm rising air
- which creates a low pressure belt
- and cool falling air which creates a high pressure belt
what are loops or cells composed of
- they are composed of warm rising air
- which creates a low pressure belt
- and cool falling air
- which creates a high pressure belt
how many loops are there in each hemisphere
three
why is there a low pressure belt at the equator
- at the equator the sun warms the earth
- which transfers heat to the air above
- causing the air to rise
- this creates a low pressure belt with rising air, clouds and rain
what happens to the warm air at the equator
- it rises and cools
- and moves out the 30 degrees north and south of the equator
why is there a high pressure belt 30 degrees from the equator
- the previously warm air from the equator cools
- causing it to sink
- creating a high pressure belt with cloudless skies and very low rainfall
how does the cool air that has reached the ground surface move
- surface winds either blow it back to the equator
- or towards the poles
what are trade winds and what do they specifically do
- surface winds blowing towards the equator
- they bow from the south east in the southern hemisphere
- and from the north east in the northern hemisphere
- at the equator the trade winds meet and are heated by the sun
- causing them to rise and form clouds
what are westerlies and what do they specifically do
- surface winds blowing towards the poles
- they blow from the north west in the southern hemisphere
- and from the south west from the northern hemisphere
what happens at 60 degrees north and south of the equator
- the warmer surface winds meet the cold air from the poles
- the warmer air is less dense than the cold air so it rises
- creating a low pressure
what is the effect of the low pressure created at 60 degrees north an south
- some of the air moves back to the equator
- while the rest moves towards the poles
what happens to the air moving towards the poles after they have passed the 60 degree mark
- the cool air sinks creating high pressure
- the high pressure air is drawn back towards the equator as surface winds
