Fronts and Pressure
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Transcript Fronts and Pressure
Chapter 18 Notes
Weather
Fronts, pressures, clouds
Fronts - leading edge of a moving
air mass.
Pressures – areas of sinking or
rising air.
Clouds – visible mass of water or
ice in the atmosphere.
Cold Fronts
Cold air mass replaces warm air
mass.
Large clouds form –
– Cumulonimbus (dark gray storm
cloud)
– Nimbostratus (dark gray, thick snow
cloud)
Warm Front
Warm air mass replaces a cold air mass.
Produces a series of clouds:
– Cirrus (wispy and transparent)
– Cirrostratus (white veils)
– Cirrocumulus (rolled patches)
– Altostratus (gray sheet or layer)
– Altocumulus (patches or rolls)
– Stratocumulus (lumpy)
Stationary Front
Occurs when air masses stop
moving.
Noticeable temperature and wind
direction change.
Occluded Front
Occurs in a Low Pressure system.
Cold front catches up with a
warm front.
High Pressure
H
Areas of sinking air that move
clockwise – called anticlones.
Clear, nearly cloudless skies.
Pushes bad weather away
Low Pressure
L
Area of rising air in a counter-
clockwise direction called
cyclones.
Cloudy, sometimes rainy days.
Meteorology
Meteorologists are scientists who study
the causes of weather and try to predict
it.
They use maps, charts, and computers
to analyze weather data and prepare
forecasts.
Use radar to track precipitation
National Weather service tracks weather
and issues warnings and watches.
Weather Technology
Weather balloons – carry
instruments high into atmosphere to
measure temp., pressure, and
humidity.
Satellites – in upper atmosphere;
measure temp, humidity, wind speed
and direction, solar radiation, and
give images of clouds and storms.
Weather Technology (con’t)
Weather stations – on surface;
measure temp, pressure, humidity,
rainfall, and wind speed and
direction.
Computers – process gathered
info quickly and help forecasters
make predictions using
calculations.
Weather Maps
The figure below shows what various
weather symbols mean.
Reading Weather Maps
This is the type of weather map produced
by the National Weather Service. It shows
data collected from many weather stations.
Reading Weather Maps
Weather maps in
newspapers use
symbols to show
fronts, high- and lowpressure areas, and
precipitation. Color
bands indicate
different temperature
ranges.
Skills activity
Cumulonimbus
Cirrus
Cirrostratus
Cirrocumulus
Altostratus
Altocumulus
Nimbostratus
Stratocumulus