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 Cumulonimbus(dark gray storm cloud) –Nimbostratus Nimbostratus(dark gray, thick snow cloud)

Warm Front  Warm air mass replaces a cold air mass.  Produces a series of clouds: –Cirrus Cirrus(wispy and transparent) –Cirrostratus Cirrostratus(white veils) –Cirrocumulus Cirrocumulus(rolled patches) –Altostratus Altostratus(gray sheet or layer) –Altocumulus Altocumulus(patches or rolls) –Stratocumulus 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  Areas of sinking air that move clockwise – called anticlones.  Clear, nearly cloudless skies.  Pushes bad weather away H

Low Pressure  Area of rising air in a counter- clockwise direction called cyclones.  Cloudy, sometimes rainy days. L

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 low- pressure areas, and precipitation. Color bands indicate different temperature ranges.

Skills activity

Cumulonimbus

Cirrus

Cirrostratus

Cirrocumulus

Altostratus

Altocumulus

Nimbostratus

Stratocumulus