Download Fronts Information

Fronts Information
The intersection of two air masses with
different properties is called a FRONT
Image from: http://www.public.iastate.edu/~mt206/
The four types of fronts are shown here:
Front Symbols:
(1) COLD
COLD FRONT
(3) STATIONARY
STATIONARY
(2) WARM
(4) OCCLUDED
WARM FRONT
STATIONARY
FRONT
OCCLUDED
FRONT
The “lumps and teeth”
teeth” are ALWAYS pointing
the direction the front is moving!
Cold Front
What direction are the fronts moving?
http://www.public.iastate.edu/~mt206/
Criteria for locating a front:
(1) Temperature change over a short distance
(2) Dew point change over a short distance
(3) Shift in wind direction
(4) Clouds and Precipitation
Warm Front
Image from: http://www.public.iastate.edu/~mt206/
General Patterns:
Warm Front:
Cold Front:
• Warm air moves into an area
that has cooler air.
• Cold air moves into and area
that has warmer air.
• Warm air moves up and over
cooler air at a gentle angle.
• Cold air forces its way under
warmer air causing the warm
air to rise rapidly at a steep
angle.
• Has different weather
patterns dependent upon the
stability of the air.
• Precipitation occurs BEFORE
the front passes.
• Generally high winds and
rapid drop in temperature.
• In stable air precipitation is
generally steady light to
moderate rain for long periods.
• Precipitation can be heavy
and often has thunderstorms.
• General cloud types stable
air: cirrus, cirrostratus,
altostratus, nimbostratus,
stratus, stratocumulus as the
front approaches and passes.
• In unstable air can develop
heavy rain and thunderstorms
for long periods.
• Generally move slowly (~ 15
mph)
• Precipitation occurs AFTER
the front has passed.
• Move very rapidly (~ 40 mph)
• General cloud types:
Cirrus, cirrostratus,
altocumulus, cumulonimbus
and cumulus as the front
approaches and passes.
Stationary Front:
Occluded Front:
• Occurs when a front stops
moving. This occurs
because upper air flow is
parallel to the boundary
between warm and cool air
rather than at an angle to
it.
•Generally thought of as a “cold
front catching up to a warm front”
front”
• Stationary fronts can
bring several days of light
to moderate rain or snow.
• Associated weather is similar to
a warm front as the occluded
front approaches.
•once the front has passed, the
associated weather is similar to a
cold front.
•There are two types of occluded
fronts:
• A Warm occlusion when the
air behind the front is warmer
than the air ahead.
• A Cold occlusion when the air
behind the front is colder than
the air ahead. Most common
type.