Day 46
Investigation 9 part 1Air Masses
Earth’s Weather
• Earth’s weather happen where?
Troposphere
Troposphere
Closest to Earth's surface
10 to 24 km (6 to 15
miles) thick
Contains dust, water vapor, and clouds
Greatest variation in temperature, humidity and
pressure
Densest layer, 80% of
atmosphere mass
Stagnant Air
• An air mass that stays over a portion of Earth’s surface for a long time and doesn’t move
• Can form over any part of the Earth– Usually forms over areas with uniform surfaces with few
mountains– Called source regions
• Stagnant air changes, depending upon the type of surface below the air
Air Masses
Large bodies of air that stagnant
over Earth’s surface
Large thick bodies of air
that are uniform in temperature and humidity
Characteristics
LargeThick
Uniform
Hundreds of miles across
Extend into the
troposphere 6 to 8 miles
Same temperature
and humidity
North American Air Masses
• Location B(northern Canada)
• Characteristics of the Air?– Cold– Dry
North American Air Masses
• Location D (Gulf of Mexico)
• Characteristics of the Air?– Warm– Humid
North American Air Masses
• Meteorologists use a code when making notes about the air masses
• Combine the names of air masses– Continental (c) - land– Maritime (m) - ocean or sea– Polar (P) - near the poles– Tropical (T) - tropical
North American Air Masses
• Location B– Located over Canada– Continental polar air
mass
• Continental Polar– Air mass that forms over
cold land
• Location D– Located in the Gulf of Mexico– Maritime tropical air mass
• Maritime Tropical– Air mass that forms over
warm water
• Maritime - anything to do with oceans or seas
North American
Air Masses
Determine the air mass code for each air mass
Don’t forget:Lower case term will go first !!!!
North American
Air Masses
mP
cPmP
cT
mTmT
Air MassesFormation
No Air Masses are formed here
Air is moving
Does not stagnate
Does not pick up the characteristics from the surface below
Air MassesFormation
Coldest air masses form here in the winter
Warmest air masses form here in the summer
Called the Horse Latitudes
Balloon Demo.
• Let’s take the large plastic bag outside to see if we can create an air mass.
• How might we accomplish this?
Solar Balloon Demonstration
• Take page 55 of of your lab book.• Answer questions 1-4 after the
demonstration.
Solar Balloon Discussion
• Why is the bag starting to float?• What is happening to the temperature and
density of the air inside the bag?• What is happening to the plastic bag itself?
Describe any changes you observe.
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