Transcript Weather and Climate

Weather and Climate

Weather is the short term (day to day)
conditions of the atmosphere.






Temperature
Precipitation
Humidity
Cloud cover
Wind
Air pressure
Climate

Involves the key
weather variables



Temperature
Moisture
Air pressure

But does so in terms of
patterns over the
course of decades.
Earth – Sun relationship




The Earth is attracted to the sun as a result
of the gravitational pull of the sun.
The earth revolves around the sun once
every year. (365.25 days)
The Earth is tilted at an angle of 23.5
degrees throughout its orbit.
The Earth rotates on its own axis once each
24hrs.
Equinox


Because of the earth’s tilt there are only 2
times during the year when the sun shines
equally on both the Northern and Southern
Hemispheres: late March (20-23rd)
late September (20-23rd)
These times of the year are called equinoxes
Solstices





The times of the year when either the Northern or
Southern Hemispheres receive the most sunlight are
called solstices.
These occur during/around June 21(longest day of
the year in NH) and December 22 (shortest day of
the year in the NH)
Observe seasonal changes in the amount of sunlight
reaching locations on Earth.
Explore a model of Earth's yearly revolution around
the sun.
Climate Controls: Latitude
Solar Radiation
Solar Radiation
Cloud Cover and Temperature

During the day, the
earth is heated by
the sun. If skies
are clear, more
heat reaches the
earth's surface (as
in the diagram
below). This leads
to warmer
temperatures.
Cloud Cover and Temperature

However, if skies are
cloudy, some of the
sun's rays are reflected
off the cloud droplets
back into space.
Therefore, less of the
sun's energy is able to
reach the earth's
surface, which causes
the earth to heat up
more slowly. This leads
to cooler temperatures.
Cloud Cover and Temperature

At night cloud
cover has the
opposite effect. If
skies are clear,
heat emitted from
the earth's
surface freely
escapes into
space, resulting
in colder
temperatures.
Cloud Cover and Temperature

However, if clouds
are present, some of
the heat emitted from
the earth's surface is
trapped by the clouds
and reemitted back
towards the earth. As
a result,
temperatures
decrease more
slowly than if the
skies were clear.
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fcst/tmps/cld.rxml