Download Weather Fronts 2016

Clouds
What they tell us about the weather
Spring funnel cloud over Willard, Utah 2003
Cloud coverage
581-586
How to show Cloud Coverage
• On a weather map
meteorologists use circles
shaded differently to show
the cloud coverage.
Determine Cloud Coverage
• 1st Way: look out side
• 2nd Way: Satellite Imagery
• Infrared
• Visible
• Water Vapor
Infrared Satellite Imagery
• Measure the
heat/energy
from the clouds
• Strong
thunderstorms
tops will appear
cold.
Water Vapor Satellite Imagery
• Measure the
water vapor in
the upper
atmosphere.
• Highest humidity
will be the white
areas and the
lowest humidity
areas are the
dark regions.
• Predict heavy
precipitation
Visible Satellite Imagery
• The Sunlight
bouncing off the
clouds making them
appear white
(sunrise hasn’t
happened in parts
that are dark).
Cloud Types
Why learn about clouds
• The purpose of learning about clouds is to
understand what type of weather is associated with
each.
• Knowing the clouds will help you predict what type
of weather is coming or could happen.
• When could you use this?
• Boating
• Camping
Cirrus
• White, feathery, wispy
• First sign of an approaching warm front
Cirrostratus
• Sheet like
• Cover entire sky
• When light pass through
the ice crystals it can
produce a ring or halo.
• Sign that a warm front is
getting closer
Cumulus
• Puffy, flat base
• Form when moist, warm air bubbles vertically from
Earth’s surface
Cumulonimbus
• Top shaped like an anvil
• Very dense with water
• Weather
• Hail, lightning, tornadoes,
thunder, and heavy rain
• Altitude: A few hundred
meters to 12,000 meters
Stratus
• Gray color and flat
• Develops horizontally, covers entire sky
• Little or no precipitation
Altostratus
• Gray looking
• Dense sheet like layers, see sun through it
Nimbostratus
• Dark, gray
• Continuous precipitation
Air Masses
Air Mass Types
and locations
• Air Mass: Large body of air of
similar temperature and
humidity
• By putting the symbols together
you are able to describe both
the temperature and moisture of
the air mass
Symbol
Name
Type
c
Continental Dry
m
Maritime
Wet
P
Polar
Cold
T
Tropical
warm
When two air masses meet…
• Frontal zone/Front: the area where two air masses
of different temperatures meet
• What happens when a cold and warm air mass
meet? Which will go over the other and why?
• The warm air mass will always go over the other
because the cold air is more dense.
• Warm air goes over the cold. Uplifting of warm air
(which may contain much moisture) causes warm
air to cool, which leads to condensation and the
possibility of precipitation along the frontal
boundary.
Weather Fronts
Cold Front
• Cold dry stable air
mass displaces moist
unstable subtropical
air mass.
• Symbol is blue
triangles, arrows
point the direction
the front is moving.
Weather Elements Prior to Front
Contact with the
Front
Temperature
Warm
Cooling suddenly Cold and getting
colder
Atmospheric
Pressure
Decreasing
steadily
Leveling off then Increasing
increasing
steadily
Winds
South to
southeast
Variable and
gusty
West to
northwest
Showers
Heavy rain or
snow, hail
sometimes
Showers then
clearing
Cold
Front Precipitation
Clouds
Cirrus and
Cumulus and
cirrostratus
cumulonimbus
changing later to
cumulus and
cumulonimbus
After front passes
Cumulus
Warm Front
• Warm, subtropical, moist, air mass
replaces a slower moving cold, dry,
polar air mass
• Symbol: red line with red semi-circles,
semi-circles point to the direction the
front is moving.
Warm
Front
Weather Element
Prior to the front
Contact with the
Front
Front has passed
Temperature
Cool
Warming
suddenly
Warmer then
leveling off
Atmospheric
Pressure
Decreasing
steadily
Leveling off
Slight rise
followed by a
decrease
Winds
South to
southeast
Variable
South to
southwest
Precipitation
Showers, snow,
sleet or drizzle
Light drizzle
None
Clouds
Cirrus,
cirrostratus,
altostratus,
nimbostratus,
and then stratus
Stratus,
sometimes
cumulonimbus
Clearing with
scattered stratus,
sometimes
scattered
cumulonimbus
Occluded
• Fast moving cold
front overtakes a
slower moving warm
front
• Two types
• Cold: “air behind the
front is colder than
the air ahead of the
front.”
• Warm: air behind is
warmer than the air
ahead of the front.
• Symbol: mixture of
purple triangles and
semi-circle
Stationary Boundaries
• “Frontal zones where air masses are not moving
against each other…”
• “Wind blow towards the front from opposite
directions”
• Symbol: mixture of blue triangles and red semicircles
Tornados
• Movie
• How they work