Air Masses and Weather

Origin of an Air Mass Air Mass: A large body of air in the lower troposphere that has similar characteristics throughout Characteristics: Several kilometers in diameter Several kilometers high Temperature and humidity are nearly uniform throughout an air mass

What type of characteristics does as air mass have throughout? Similar

Temperature and Moisture Level These characteristics depend on where the air mass originates. Ex: if an air mass stays in a polar region for an extended period of time, it becomes cold as well. When an air mass travels from one area to another, it takes with it the temperature and humidity of its place of origin As it travels, its characteristics may change

What happens when an air mass travels? it takes with it the temperature and humidity of its place of origin

Types of Air Masses Classification of air masses is based on their place of origin The names are two part: Temperature- arctic, polar, or tropical region Humidity- land (continental) or marine (maritime)

What two characteristics are used to classify air masses? Temperature and humidity

Continental Arctic Originate in Arctic regions Air becomes extremely cold Capable of causing extreme cold waves as they move into new regions Very dry

Continental Polar Originate over the inland regions of Alaska and Canada Slightly warmer than Continental Arctic Usually dry If travels over large body of water, can create precipitation

Maritime Polar Originate over the ocean in high latitudes Cold and damp Produces fog, clouds, and precipitation “nor’easters” heavy snowstorms from the North Atlantic

Maritime Tropical Originate over a warm tropical ocean Warm and moist Produce thunderstorms in the heat of the day

Continental Tropical Originate over deserts Hot and dry Produce tremendous heat waves

What are the 5 types of air masses? Continental Arctic, Continental Polar, Maritime Polar, Maritime Tropical, and Continental Tropical

Fronts

Fronts Front: The boundary that separates opposing air masses Characteristics Width: 200 meters to 200 Kilometers Height: up to 5 kilometers Length: up to 2000 kilometers Usually bring precipitation Most common at mid latitudes Where polar and tropical air masses meet

The boundary that separates opposing air masses What is a front? The boundary that separates opposing air masses

Shape of a front The less dense air mass is forced to rise over the denser air mass. This makes the front wedge shaped.

Cold Front Boundary between an advancing cold air mass and the warmer air mass it is displacing Steep slope Narrow band of precipitation Moves quickly

Warm Front Warm air displaces cold air Gradual slope Cirrus clouds Steady rain or snow for extended time Weather warms when it passes

Occluded Front Occluded: When a cold front catches a warm front Causes cloudiness and precipitation

Stationary Fronts Stationary: When a front is not moving Causes cloudiness and precipitation If stationary too long, flooding may occur

What happens if a stationary front remains in the same place for too long? flooding