Transcript Objective: Air Masses and Weather Fronts

Objective: Air Masses, Cyclones,
Anti-cyclones and Weather
Fronts
Do Now: List some symbols you
may see on a weather map on
T.V. or in a newspaper
Air Mass
 An air mass is a large section of air that has
the same temperature and moisture content
throughout
 Air masses gain these characteristics by
staying over an area of earth for a long
period of time
 Example: If an air mass stays over a warm
ocean, the air will be both warm and wet.
Air Masses In The United States
mP:
Maritime
Polar
mP:
Maritime Polar
mT:
Maritime Tropical
cP:
Continental
Polar
cT:
Continental
Tropical
mT:
Maritime
Tropical
Low Pressure Systems
A.K.A. Cyclones
 Bad news!!!! =(
 Like low grades, low pressure systems are
bad
 Low pressure means hot and humid air, lots
of clouds, and high probability of
precipitation
 Low’s are associated with most storms and
the severest of weather
BOOOOOOOOOOOO!!!!!!!
 The center of a cyclone
has the lowest pressure
 A Giant L is placed in the
center
 Winds blow in towards the
center and curve
counterclockwise due to the
Corilois Effect
 Remember– counters in
your house are low!!
High Pressure Systems
A.K.A The Anti-cyclone





Like high grades, high pressure is good.
Clear skies
Cooler air
Light winds
Little or no moisture
HIGH’S
 Opposite of the low
H
 A Giant
is placed in the
center
 Winds blow out from the
center towards lower
pressures
 Winds curve clockwise due
to the Coriolis Effect
 Remember– Clocks are
high on the wall
Fronts
 A front is a boundary where two
DIFFERENT air masses meet
 There is always changes in wind speed,
wind direction, air pressure, cloud cover and
precipitation when a front passes over an
area
 The front symbols mark where the front of a
front is.
Cold Front
1. Cold air mass moves in on
a warm air mass
2. Warm air rises quickly
because it is less dense
3. As air rises it cools and
the water condenses to a
liquid
4. High, puffy, storm clouds
form quickly
5. Heavy precipitation falls
for a short time
6. Cold fronts are
represented by a line of
blue triangles pointing in
the direction of movement
Warm Front
1. A warm air mass
moves in on a cold air
mass
2. The warm air rises up
the cold air mass
slowly.
3. The air cools slowly
and the water vapor
condenses slowly.
4. Thin, wispy, low clouds
form
5. Light precipitation falls
for an extended period
of time
Cold vs. Warm
Stationary Front
 When a warm or cold front
stops moving, it becomes a
stationary front.
 Once this boundary
resumes its forward motion,
it once again becomes a
warm front or cold front.
 A stationary front is
represented by alternating
blue and red lines with blue
triangles pointing towards
the warmer air and red
semicircles pointing towards
the colder air.