air masses and fronts warm up: what type of rock is formed from cooling lava?
Post on 19-Dec-2015
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Air Masses and Fronts
Warm Up: What type of rock is formed from cooling lava?
Air Mass VIDEO Clip
Air Masses• Air masses have the same properties as the surface
over which it develops:
Maritime = WetContinental = DryPolar = ColdTropical = Warm
mP = wet/cold
cP = dry/cold
mT = wet/warm
cT = dry/warm
Air Masses in North America
Fronts
• A front is the boundary where two air masses meet.
• Types of fronts:1. Warm Front
2. Cold Front
3. Occluded Front
4. Stationary Front
WARM AIR
COLD AIR
FRONT
Front VIDEO Clip
Cold Front• Cold dense air
pushes under a warm air mass.
• The cold dense air moves faster and causes the warm air rises quickly.
• Narrow bands of violent storms form.
Why do cold fronts bring heavy rain and storms?
• Cold air interacting with warm air = a sudden drop in temperature = CONDENSATION occurs quickly and a fast difference in pressure
• Creates cumulonimbus clouds• Cold dense fast moving air = high winds
What you see in a weather map!
Cold Front Video Clip
Warm Front
• Warm air slides over departing cold air.
• Large bands of precipitation form
Why do warm fronts bring mild weather?
• It’s more difficult for the warm air to move against the cold dense air so there is a gradual difference in pressure and temperature
What you see in a weather map!
Warm Front Video Clip
Occluded Front• Two cold air masses merge and force
warm air between them to rise quickly.
• Strong winds and heavy precipitation will occur.
Why do occluded fronts bring heavy rain and storms?
• Cold air that is more dense moves into an area of low pressure = CONDENSATION occurs quickly
• Forms cumulonimbus and nimbostratus clouds
What you see in a weather map!
Stationary Front
• Warm and/or cold front stops moving.
• Light wind and precipitation may occur across the front boundary.
Why do stationary fronts bring long light precipitation?
• Neither front is strong enough to move the other
• Can stay put for days• Differences in temperature = rain or snow
What you see in a weather map!
Cyclones and Anticyclones• Areas of HIGH and LOW pressure• Cyclone = LOW PRESSURE = spin
counterclockwise = associated with storms and precipitation
• Anticyclone = HIGH PRESSURE = spin clockwise = associated with fair weather.
Cyclones and Anticyclones in the USA
Cyclone Video Clip
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