Air Masses  Areas of air that have about the same density, temperature, humidity, and pressure.  Cold air masses usually move south towards the equator.  Warm air masses usually move north away from the equator.

Types of air masses  Maritime (m) – moist air from over the water  Continental (c) – dry air from over the land  Polar (P) – cool air masses from a sub polar region  Tropical (T) – warm air from near equator  Arctic (A) – VERY cold air coming from the Arctic  Combine the above to form air masses: –mP, cP, mT, cT, cA

Fronts  Fronts are where air masses meet  Weather most often occurs along “fronts”  Four different types of fronts: –Cold Fronts –Warm fronts –Occluded fronts –Stationary fronts

Cold Front

Warm Front

Occluded Front  When a cold front catches up to a warm front

Stationary Front

Clouds and precipitation at the fronts

Occluded Front clouds and precipitation

Low pressure and high pressure systems

(Backwards from previous slide)

“Cyclogenesis”

Typical Low Pressure System

More Animations  5_cnWfronts.html 5_cnWfronts.html 5_cnWfronts.html  nt/visualizations/es2002/es2002page01.cfm?chapter_no=vi sualization nt/visualizations/es2002/es2002page01.cfm?chapter_no=vi sualization nt/visualizations/es2002/es2002page01.cfm?chapter_no=vi sualization  Cyclogenesis Cyclogenesis Cyclogenesis

Assignment  In groups of 2 (assigned by cards): Locate the Air masses on map with temperatures provided. After you do this, compare the data with a map that has weather stations on it. It should take no more then 15 minutes to do this.