WHAT MAKES THE WIND BLOW?. Recall the effect of solar radiation.
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Transcript of WHAT MAKES THE WIND BLOW?. Recall the effect of solar radiation.
WHAT MAKES THE WIND BLOW?
Recall the effect of solar radiation
At the Equator
Atmosphere is heated
Air becomes less dense and rises
Rising air creates low pressure at the equator
Air cools as it rises
Water vapor condenses (rains) as the air cools with increasing altitude
As air mass cools it increases in density and decends bac to the surface in the subtropics (30o N and S), creating high pressure
This circulation is called the Hadley Cell
Air always move from an area ofHigh pressure to an area of Low
pressure
Hadley Cell
Global Wind Pattern
Global Winds• Greater heating of the atmosphere over equator causes air to
expand, become less dense and rise- this is a permanent low
pressure belt - Very humid
• Warm equatorial air then travels some distance north and south of equator and descends in subtropical regions around 30° latitude; when it descends, it becomes compressed and
denser and creates a high pressure belt in subtropics - Very Dry
• This descending subtropical air spreads along earth's surface both back towards the equator (these are the trade winds, between 0-30° N or S) and also to higher latitudes (westerly
wind belts, 30-60° N or S)
Coriolus EffectWhen decending air comes into contact with the earth in motion.
If the Earth didn't rotate we would only have a a single circulation cell in each hemisphere.
Because of fluid motion on a rotating sphere, Earth has three circulation cells in each
hemisphere:
Sea Breezes