warm up. poirier meteorology the study of processes that govern earth’s atmosphere to help make...
TRANSCRIPT
Warm up
Warm up
Poirier
Meteorology
The study of processes that govern Earth’s atmosphere to help make weather predictions
List as many things as you can think of that affect Earth’s atmosphere and the weather
Air Mass
A large body of air in the lower troposphere that has uniform characteristics Similar temperature Similar humidity
The interaction of air masses is what causes local weather.
North American Air Masses
What is a Weather Front?
A Front is the boundary that separates opposing air masses
Common in mid-latitudes (meeting place of polar and tropical air)
Movement – interaction of air based on density (temperature humidity)
Cold Front
Cold air mass moving in to replace warmer air More dense so moves under warmer air Pushes warmer air up (vertical flow) Brings
Thunder storms in summer Less humid air Change in wind direction Short period of precipitation
Moves about twice as fast as a warm front
Cold Front
Warm Front
Warm air moves in and displaces cold air Less dense so rises up over the cold air Shallow slope less abrupt weather change Brings
~24 hours of increasing clouds starting with cirrus
Overcast Prolonged period of precipitation After clearing warmer more humid conditions
Moves about half as fast as a cold front
Warm Front
Occluded front
When one cold front catches up with previous cold air mass Push warm air up Causes cloudiness and precipitation
Stationary Front
When a front is no longer moving forward Warmer air rises, condenses, causes
precipitation Flooding can occur
Materials hand outs Scissors Blue and red crayons Tape
Turn in question sheet when finished
Review Moving Masses
Answers
Passing of a low-pressure system
Low pressure systems can be up to 2,000 km across
Low pressure system
Warm front, then cold front Approach of warm front, clouds
increasing from cirrus to nimbostratus, steady rain
Warm front passes, temp and humidity increase, winds shift, skies clear
Approach of cold front, scattered showers or T-storms
Cold front passes, temp and humidity decrease, winds shift again, skies clear
Life cycle of a low-pressure system