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.