Transcript Slide 1

An air mass is a large pool of air having similar temperature and
moisture characteristics. An air mass occupies thousands of
square miles of the Earth's surface. Air masses are created in a
source region where they take on their characteristic
temperature and moisture content.
The jet stream flows from west to east
in wave-like patterns.
Which way will the wind blow in Louisiana? Why?
West to East,
Jet Streams
Fronts are boundaries between
contrasting masses of air.
Cold fronts are those where moving cold air
slides under warm air The steep slope pushes the air ahead of it
rapidly upwards and vertically developed clouds (cumulus) are produced along the front.
Warm Air
Cold Air
Heavy Rain often occurs. Cold front Symbol
With greatly contrasting air masses on either side of the front, and
potentially unstable conditions, violent weather can form. Towering
cumulonimbus clouds are common along cold fronts producing intense
downpours of rain lasting for a relatively short period of time. Tornadoes
can form under the most extreme conditions ahead of an advancing cold
front.
A warm front is where moving warm air
pushes over cold air. As with a warm front, you experience a drop in
the atmospheric pressure as the front approaches. The warm front slopes gently up into
the troposphere that has a direct bearing on the kinds of clouds that are produced. As
the warm air behind the front collides with the cooler air ahead, the warmer less dense
air is forced to glide upward.
Warm Air
Light or moderate Rain often occurs.
Warm front Symbol
Cool Air
Once the warm front passes your location you'll notice an increase in temperature
and air pressure. Soon the stratus clouds of the warm front give way to broken
and clearing skies. As the warm sector moves into your location you will notice an
increase in the humidity of the air
Figure WS.4 Front Symbols
Air particles moving
from areas
of high pressure to
areas of low pressure.
Caused by uneven
heating of the Earth.
Moving cold air slides under
warm air.
COLD FRONT
Moving warm air pushes over
cold air.
WARM FRONT
This symbol:
WARM FRONT
This symbol:
COLD FRONT
Heavy Rain often occurs.
COLD FRONT
Light or moderate rain
precipitation can occur.
WARM FRONT
WIND