Air MassesAir Masses

What is an Air Mass?What is an Air Mass?

A huge section of the lower troposphereA huge section of the lower troposphere Contains air of same temperature and Contains air of same temperature and

humidityhumidity Forms in regions of light windForms in regions of light wind Maintains composition for daysMaintains composition for days Named for source regionNamed for source region

If Ground is colder:If Ground is colder:

Bottom of air mass cooledBottom of air mass cooled Causing:Causing:

-bottom layer to be stable-bottom layer to be stable

-inversions (trapping dust/pollutants)-inversions (trapping dust/pollutants)

-poor visibility-poor visibility

-condensation occurs (dew/fog/drizzle)-condensation occurs (dew/fog/drizzle)

If Ground is Warmer:If Ground is Warmer:

Bottom of air mass warmedBottom of air mass warmed Causing:Causing: -bottom to be unstable-bottom to be unstable -convection currents occur (Cumulus clds)-convection currents occur (Cumulus clds) -air pollution mixed-air pollution mixed -visibility good-visibility good - fair weather if low humidity- fair weather if low humidity -showers if higher humidity-showers if higher humidity

TYPES OF AIR MASSESTYPES OF AIR MASSES

Maritime- (m)- form over ocean-humidMaritime- (m)- form over ocean-humid Continental – (c) form over land-dryContinental – (c) form over land-dry Tropical- (T)- form near equator-warmTropical- (T)- form near equator-warm Polar – (P) – form at high latitudes-coolPolar – (P) – form at high latitudes-cool Arctic-(A)- form at highest latitudes-coldArctic-(A)- form at highest latitudes-cold

Maritime Tropical- mTMaritime Tropical- mT

Continental Polar -cPContinental Polar -cP

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