Post on 27-Dec-2015
Air Mass Defined:
A large body of air found in the lower troposphere that is similar throughout in: humidity (wetness/dryness) and temperature
Air Masses
cA- continental arctic, very cold and dry (from northern Alaska/Canada)
cP- continental polar, cold and dry (from southern Alaska/Canada) (if travels over H2O, can cause snow)
mP- maritime polar, cold and wet (from north pacific/Atlantic ocean)
mT- maritime tropical, warm and wet (from gulf of Mexico)
cT- continental tropical, warm and dry (from Mexico and central America) (since dry=no clouds)
Jet StreamsA fast moving stream
of air found in the upper atmosphere (like a “river of air”)
Found at 30 degrees and 60 degrees north and south of the equator (between convection cells where hot and cold air meet)
Review: Air MassesAn air mass is a large body of air that has similar
temperature and humidity
If an air mass forms over land (continental) it has low humidity
If an air mass forms over an ocean (maritime) it has high humidity
Air masses are either hot or cold
What happens when air masses run into each
other?FRONTS!
Air masses don’t mix together
The boundary where the air masses meet is called a front
Fronts are common at mid-latitudes, where tropical and polar air masses commonly meet
What happens when air masses run into each
other?Air masses have different temperatures and
humidity levels
When they collide, the more dense air mass goes under the less dense air mass
Cold FrontOccurs when a
polar (cold) air mass runs into (& replaces) a tropical (warm) air mass
The warm air is less dense and gets pushed above the cold air mass
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2002/es2002page01.cfm
Cold FrontTemperatures drop, and there is usually
precipitation
Thunderstorms are usually a result of a cold front
Warm FrontWarm front-
when warm (less dense) air moves forward (advances) and replaces cold air: forms a wedge shape. http://www.classzone.com/books/
earth_science/terc/content/visualizations/es2002/es2002page01.cfm
Warm FrontResults in warmer temperatures, often
higher humidity
Usually precipitation for several days
http://www.atmosphere.mpg.de/enid/1__Weather___Fronts/__Worksheet_1_4ap.html
Stationary FrontOccurs when neither the warm air or the
cold air is advancing
The less dense warm air will rise above the cold air
Stationary FrontClouds and precipitation occur
If a stationary front stays for too long, flooding can occur
Occluded FrontOccurs when a cold front catches up with a warm
front
Cold fronts move twice as fast as warm fronts