The
weather is driven by the heat from the sun.
Near the equator the sun’s rays hit directly. The earth there absorbs a great deal of the sun’s energy
and the weather is hot.
In
polar regions the sun hits at a shallow angle.
More of the sun’s energy is ‘bounced” back into space and
the weather is cold.
Besides
warming the earth and causing the circulation of air, the sun causes
evaporation of water from the rivers and oceans into our atmosphere.
Water in the air accounts for clouds, fog, rain, snow, hail, dew,
and frost.
Air
movement from these areas (the equator and the polar regions) creates
our weather. The warm air along the equator rises and cool air from the
North and South Poles moves toward the equator.
The movement of this warm and cool air and the rotation of the
earth cause a global circulation of air.
The
name for the way the winds swirl and turn around the earth because of
its rotation is called the Coriolis
Effect.
These moving masses of air warm up and cool down, rise and fall,
collide, and carry precipitation.
This circulation of air is mainly responsible for the weather
conditions around the world.
In
the United States, our weather is determined by two strong patterns of
wind called the jetstreams.
These bands of moving air run from east to west, basically split
our nation in half.
One
jetstream brings cold air from the north.
The other brings much warmer and moister air from the south.
The
northern part receives its cold airflow from the North Pole, Alaska, and
Canada. The
southern part of the country receives warm moist air from Mexico and the
equator.
Usually
it takes approximately 7-8 days for the weather systems originating
along the western coast to move across the entire United States.
Predictions of future weather may be made by studying what weather is
approaching from the western coast.
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climate
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Air
Movements