Air Masses Fronts What is an AIR MASS

Air Masses & Fronts

What is an AIR MASS? • An air mass is a huge body of air that influences weather. • Scientists classify air masses based on: TEMPERATURE and HUMIDITY

Air Masses are named based on where they FORMED… = TROPICAL = POLAR = MARITIME (means sea… wet) = CONTINENTAL (means land… dry)

How are Air Masses named? MARITIME CONTINENTAL TROPICAL MARITIME CONTINENTAL POLAR

North American Air Masses MARITIME POLAR MARITIME TROPICAL CONTINENTAL POLAR CONTINENTAL TROPICAL MARITIME POLAR MARITIME TROPICAL

How do these air masses move? MARITIME POLAR CONTINENTAL POLAR MARITIME POLAR Jet Stream. That’s why weather generally moves WEST to EAST in the U. S. Westerlies Prevailing MARITIME TROPICAL CONTINENTAL TROPICAL MARITIME TROPICAL

What happens when air masses meet? • Air masses don’t mix easily. • The line between air masses is called a front.

COLD FRONTS

WARM FRONTS

Watch the Brain. Pop video on “Weather” and write down 2 things you learned.

Use your textbook (pg. 133 -135) to fill out the chart.

Compare/Contrast Chart - Types of Fronts Front Cold Front Warm Front Stationary Front Occluded Front How it Forms A fast-moving cold air mass overtakes a warm air mass. Type of Weather Clouds form. If warm air is humid, rain/snow may fall. Possible thunderstorms.

Compare/Contrast Chart - Types of Fronts Front How it Forms Cold Front A fast-moving cold air mass overtakes a warm air mass. Warm Front Stationary Front Occluded Front Type of Weather Clouds form. If warm air is humid, rain/snow may fall. Possible thunderstorms. A warm air mass Scattered clouds. overtakes a slow-moving Light rain or snow. cold air mass. May last several days.

Compare/Contrast Chart - Types of Fronts Front How it Forms Cold Front A fast-moving cold air mass overtakes a warm air mass. Warm Front Type of Weather Clouds form. If warm air is humid, rain/snow may fall. Possible thunderstorms. A warm air mass overtakes Scattered clouds. a slow-moving cold air mass. Light rain or snow. May last several days. Stationary Front Cold and warm air meet, Rain, snow, clouds, or but neither can move the fog that may last for other. Creates “standoff” days. Occluded Front

Compare/Contrast Chart - Types of Fronts Front How it Forms Cold Front A fast-moving cold air mass overtakes a warm air mass. Warm Front Type of Weather Clouds form. If warm air is humid, rain/snow may fall. Possible thunderstorms. A warm air mass overtakes Scattered clouds. a slow-moving cold air mass. Light rain or snow. May last several days. Stationary Front Cold and warm air meet, but Rain, snow, clouds, or fog neither can move the other. that may last for days. Creates “standoff” Occluded Front A warm air mass is Temperature gets cooler. caught between 2 cooler Clouds and rain may air masses. Warm air form. mass is pushed up.

Surface Map (Fronts & Precipitation) Precipitation High Pressure Low Pressure H L Warm Front Occluded Front Cold Front Stationary Front

Temperature Map

Which Whatdirection will happen is the to warm the weather frontinmoving? Little Rock? 12°C 19°C 14°C 20°C 25°C 28°C 15°C 21°C 26°C 30°C High Pressure Low Pressure H L Wednesday Tuesday Monday Weather Little Rock, AR Sun Clouds Partly & clear Sunny & Rain skies Warmer Cool = =15°C 21°C 26°C Warm Front Occluded Front Cold Front Stationary Front

What Which will direction happenis tothe weather cold front in Nashville? moving? 10°C 8°C 11°C 10°C Thursday Saturday Friday Weather Nashville, TN 15°C 10°C 20°C Thunderstorms Partly Sunny Cooler Warm Cool ===10°C 20°C 15°C High Pressure Low Pressure H L Warm Front Occluded Front Cold Front Stationary Front