Download Weather SYstems

WEATHER
SYSTEMS
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
PRESSURE SYSTEMS
Low pressure systems
• Warmer, less dense air being lifted off the surface
• Unstable and stormy conditions.
• Form cyclones
PRESSURE SYSTEMS
High pressure systems
• Cooler more dense air falling to the earth’s surface.
• Generally nice conditions and stable weather
• Can form anticyclones
AIR MASSES AND WEATHER
CONDITIONS
Air masses vary in temperature and moisture depending on where
they form:
• Continental = dry (over land)
• Maritime = wet (over water)
• Polar = cold (higher latitude)
• Tropical = warm (lower latitude)
AIR MASSES AND WEATHER
CONDITIONS
Four Major Air Masses
Continental Polar = dry and cold
Continental Tropical = dry and warm
Maritime Polar = moist and cool
Maritime Tropical = moist and warm
• Polar air masses tend to move southward
• Tropical air masses tend to move northward.
• Polar and Tropical air masses typically meet in the mid-latitudes.
Where air masses of different temperatures meet it is known as a
front.
WEATHER FRONTS
• https://www.youtube.com/watch?v=G7Ewqm0YHUI
TYPES OF FRONTS
1) Warm Front
• Warm air mass overtakes a cold air mass
• Pressure decreases (warm air is less dense)
• Typically bring light rain with cloud cover
2) Cold Front
• Cold air mass overtakes a warm
one
• Pressure increases (cold air is
heavier)
• Short periods of heavy rain
followed by clear skies.
3) Stationary Front
• Cold and warm air masses meet and stop
• Bring long periods of rain or snow (several days)
4) Occluded Front
• Cold air mass traps a warm air mass above the ground.
• Often signals the end of a stormy low pressure system.
THREE DAYS OF CANADIAN WEATHER
• Discuss Pages 550-552