Notes for Unit on Climate and Weather (Standard 6 Obj. 2)
Climate is the long-term average of the weather for a certain location. Some
climatologists say that you need to average at least 30 years of weather data before you
can call it climate. A meteorologist studies weather. A climatologist studies climate. A
meteorologist uses technology such as weather satellites to see storms forming over the
ocean or Doppler radar to view approaching storms. A meteorologist might also use a
thermometer, a barometer (to measure air pressure), or a rain gage to measure
precipitation. A climatologist might use a computer to collect and average historical
weather records.
The equator gets the most direct sunlight (radiation) so on average it is the warmest area
on the earth. The North and South poles are cold because they get less direct sunlight.
Convection currents occur wherever there is a difference in temperature. Warm air
rises at the equator and cooler air rushes in from the north and south to take the place of
the rising warm air. These winds are called global convection currents because they
happen all around the globe. Convection currents in the air and the oceans help move
heat away from the equator toward the poles. If we had no air currents or ocean currents,
the heat would build up at the equator making it too hot, and the poles would be too cold
because the heat wouldn’t move from the equator to the poles.
Because the earth is spinning, air currents and ocean currents also spin. The currents tend
to curve clockwise in the northern hemisphere and counterclockwise in the southern
hemisphere. This is known as the Coriolis Effect.
Because of global convection and the Coriolis Effect, winds in Utah generally blow from
the west. We say that Utah lies in a prevailing westerly. Wind direction has a huge
effect on climates. Winds that come from the ocean bring moisture. Winds that come
from land are usually dry.
The topography (mountains) have a huge effect on climate. Most of the storms that
reach Utah form over the Pacific Ocean and the westerly winds carry the storms toward
Utah. Large mountain ranges such as the Sierra Nevada Mountains cause much of the
moisture to precipitate out of the storms before they reach Utah. This is one reason why
Utah and Nevada are so dry.
Ocean currents also have a huge effect on climates. Ocean currents that come from the
north and south poles will generally be cold. Ocean currents that come from the equator
will generally be warm. Warm-water currents keep nearby land areas a little warmer in
the winter than they would be otherwise. Cold ocean currents keep nearby land areas a
little cooler in the summer than they would be otherwise. The Pacific Ocean current off
the west coast of the U.S. is a cold water current coming from the North. This cold water
cools the air as it blows across the water toward Utah.