Air masses

and Fronts

Air MassesIt is a large body of air that has fairly uniform physical properties.

Characteristics of Air Mass

1. Air mass must be large in size2. Air mass must have a uniform

and consistent makeup at all points within the air mass.

3. Air mass must be physically bound together, traveling across the atmosphere as a single unit.

HOW DO AIR MASSES FORM?

It forms when a large body of air becomes fairly stationary over a region of Earth’s surface or as air moves over a large, uniform region like an ocean.

CLASSIFICATIONS OF AIR MASSES

Maritime Polar

ArcticContinental Polar

Continental TropicalMaritime Tropical

CLASSIFICATION OF AIR MASSES

1. MARITIME AIR MASS - forms over water

2. CONTINENTAL AIR MASS – forms over land

3. POLAR AIR MASS – forms North of 50º or

South of 50º, where it is often extremely cold.

4. TROPICAL AIR MASS – originates in the

tropics, where it is warm.

AIR MASSES THAT MOST AFFECT WEATHER

• MARITIME POLAR – air masses originate over frigid North Pacific and North Atlantic Ocean, where are cool and moist, and often bring heavy precipitation to coastal areas.

• CONTINENTAL POLAR – bring cold and dry air .

• MARITIME TROPICAL – bring warm, moist air and are often accompanied by fog or rain.

• CONTINENTAL TROPICAL – bring hot, dry air.

FRONTSThe sharply

defined boundary that forms when

two unlike air masses meet.

TYPES OF FRONTS

Stationary front• When two

unlike air masses have formed a boundary but neither is moving front.

• Often result in clouds and steady rain or snow for several days.

COLD FRONTOccurs when a cold

air mass overtakes a warm air mass.

cumulus and cumulonimbus clouds

Strong winds, severe thunderstorms and hail.

Warm FrontOccurs when a

warm air mass overtakes a cold air mass.

Steady rain, heavy showers or thunderstorms.

OCCLUDED FRONTwhen a warm

air mass is caught between two cooler air masses.

1. HOW DO CLOUDS FORM?

2. WHAT ARE THE MAJOR TYPES OF CLOUDS?

ASSIGNMENT: