Transcript prevailing winds2

The Importance of Winds
Winds can be a curse . . .
. . . or a blessing!
Moon
Earth
The Moon’s temperature ranges from –153 o C to +107 o C because
it doesn’t have an atmosphere, and therefore no winds.
(low pressure)
(high pressure)
(low pressure)
Why Does Warm Air Rise & Cool Air Fall?
Convection
When a liquid or gas is heated, the
particles speed up & move further
apart, making the substance less dense.
When a liquid or gas is cooled, the
particles slow down and move closer
together, making the substance
more dense.
In a low pressure system, warm air is rising. Low pressure systems bring
precipitation (e.g.- rain, snow, hail, etc.)
In a high pressure system, cool air is falling. High pressure systems bring clear
skies and pleasant conditions.
http://www.youtube.com/watch?v=-pyC7WnvLT4
How do the Prevailing Winds Form?
Coriolis Effect
http://www.youtube.com/watch?v=mcPs_OdQOYU
The water in your toilet
DOESN’T swirl clockwise
because of the Coriolis effect!
Wind appears to bend over large distances because of the Earth’s rotation. In the
Northern hemisphere, they appear to bend towards the right; in the Southern
hemisphere, to the left.
Importance of Prevailing Winds
In Canada, the westerlies blow mid-latitude cyclones/
low pressure systems W to E across the country.
The westerlies can carry SO2 & NO2 (pollutants which cause acid rain)
from the industrial heartland of the U.S. into Canada.
The westerlies cause areas on the leeward side of lakes
(e.g.- Parry Sound & Buffalo) to get lots of lake-effect snow.