Download 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