Air Masses: Types and Characteristics

• Air masses are large bodies of air with uniform temperature and humidity, shaped by their formation location.
• Meteorologists analyze air masses to predict weather patterns.

Air Mass Characteristics

• Air mass names combine formation location (land or water) and temperature.
• Continental air masses (denoted by "c") form over land and are typically drier.
• Maritime air masses (denoted by "m") form over water and are typically moister.
• Tropical air masses (denoted by "T") are warm and form in equatorial zones.
• Polar air masses (denoted by "P") form over cooler regions.
• Arctic air masses (denoted by "A") form over the coldest regions.

Types of Air Masses

• Maritime tropical (mT): moist and warm/hot.
• Continental arctic (cA): dry and very cold.
• Maritime arctic (mA): moist and very cold.
• Maritime polar (mP): moist and cool.
• Continental polar (cP): dry and cool.
• Continental tropical (cT): dry and warm/hot.
• Maritime Polar air masses have higher humidity than Maritime Arctic air masses.

Air Mass Formation in North America

• mT air masses form off the coasts of California/Baja California and in the Gulf of Mexico/Atlantic Ocean, bringing warm, moist conditions.
• cA air masses form in northern Canada and the Arctic, bringing dry, very cold weather.
• mA air masses do not form in North America, but affect the British Isles with cold, wet, snowy weather
• mP air masses form over the Pacific off the coast of Alaska/Canada and off the Atlantic coast of Canada, bringing wet, cold, and rainy weather.
• cP air masses form in Canada, bringing dry, cold conditions.
• cT air masses develop over Mexico and the American Southwest (Texas), bringing warm, dry conditions.

How Air Masses Affect Weather

• Air masses move due to jet streams in the upper atmosphere.
• Stagnant air masses can cause prolonged weather conditions characteristic of their origin.
• Frontal boundaries occur when air masses collide, leading to weather changes.
• Cold fronts occur when a cold air mass pushes under a warm air mass, causing thunderstorms and snowstorms.
• Warm fronts occur when a warm air mass rises over a cooler air mass, leading to rain followed by warm, humid conditions.
• Cooler air masses are denser and stay near the ground, while warmer air rises.

Cloud Formation

• Rising air and moisture cause cloud formation as water droplets condense on particles.
• Cooling air temperature with altitude leads to condensation.
• Cumulus clouds form when cool air pushes under warm air; these can become cumulonimbus clouds during cold fronts, causing storms.
• Convectional lifting: Warm air rises, cools, and falls, forming cumulus clouds and convection currents, often near the equator, causing rainy, stormy conditions.
• Orographic lifting: Air masses forced over mountains cool, forming clouds and precipitation, with one side of the mountain receiving more precipitation.

Air masses are large volumes of air with uniform characteristics, influencing weather patterns. They are classified by moisture content (continental or maritime) and temperature (tropical, polar, or arctic). This classification helps meteorologists in weather prediction.