Download air masses & fronts

Air Masses & Fronts
Air Masses
Objective: to identify the different types of
air masses & where they originate from.
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)
Answer:
1. Where do cold & hot air masses originate?
2. Where do moist & dry air masses originate?
Jet Streams
 A 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)
Fronts
Objective: To identify the different types
of fronts and how they are caused
Review: Air Masses
 An 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
Fronts
 A front is a place
where two different air
masses meet
4 types of fronts:
 Each bring different types of weather
Cold Front
 Occurs 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/vi
sualizations/es2002/es2002page01.cfm
Cold Front
 Temperatures drop, and there is usually
precipitation
 Thunderstorms are usually a result of a cold
front
Warm Front
 Warm front- when
warm (less dense)
air moves forward
(advances) and
replaces cold air:
forms a wedge
shape.
http://www.classzone.com/books/earth_sci
ence/terc/content/visualizations/es2002/es
2002page01.cfm
Warm Front
 Results 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 Front
 Occurs when neither the warm air or the cold air
is advancing
 The less dense warm air will rise above the cold
air
Stationary Front
 Clouds and precipitation occur
 If a stationary front stays for too long, flooding can
occur
Occluded Front
 Occurs when a cold front catches up with a warm front
 Cold fronts move twice as fast as warm fronts
Occluded Front
 Causes cloudiness and precipitation