1. Air Masses and Weather Maps Investigation 9, Part 2
Weather and Climate
Air Masses and Weather Maps
Investigation 9, Part 2
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2. Review Air Masses Air masses: Large thick bodies of air
Uniform in temperature and humidity
Have distinct boundaries
Cover large areas of earth’s surface
Reach top of the troposphere
Names for the source region
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3. Colliding Air Masses
Cold air masses from the polar regions move south and east
Air masses don’t stay in one place
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Warm air masses from the tropics move north and east

4. Colliding Air Masses Air masses don’t stay in one place
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Movement of air masses creates opportunity for air masses of different temperatures and humidity to collide

5. Meeting of Air Masses Remember the density bottles
What is going on inside of the bottle?
Denser liquid below the less-dense one
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6. Meeting of Air Masses Imagine I reach north
Grab a cP (continental polar) air mass
Shrink it
Jam it into the bottle
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7. Meeting of Air Masses Imagine What happens to the air masses? mT cP
I reach south
Grab a mT (maritime tropical) air mass
Shrink it
Jam it into the bottle with the cP one
What happens to the air masses?
Polar air sinks because it is denser
Tropical Air lifts to the top because it is less dense mT
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8. Air Mass Model Gases and liquids have fluid movement
The liquid in the bottle represents what would happen in real life with air masses
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9. Fronts If air masses meet, a boundary forms Front
A boundary between two air masses
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10. Origin of “Fronts” Originated after World War 1
Norwegian meteorologists
The zone where 2 opposing armies clash is called a battlefront
The boundary - violent weather changes often occur
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11. Naming Fronts
Takes the name of the air mass that is moving faster and overtakes a slower air mass
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12. Cold Fronts
A boundary that forms when a cold air mass overtakes warm air mass
Clouds form
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Cold, dense air plows under warm, less dense air
Warm, humid air rises and cools

13. Weather and Cold Fronts
Effects from cold fronts happen quickly
Clouds form, can grow into thunderstorms
Rain or snow can fall
Lightning and hail
Drop in temperature
Pressure increases
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A cold front moves in
Cold front symbol on weather map

14. Warm Front
The boundary that forms when a warm air mass overtakes a cold air mass
Can be hundreds of km long
Warm air slides up over cold air at a gentle slope
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15. Weather and Warm Front Effects happen over long period of time
A warm front moves in
Effects happen over long period of time
Air pressure decreases
Temperature rises at the surface
Clouds thicken and lower (first wispy, cirrus clouds) then others (cumulostratus, altostratus, nimobostratus, stratus, possibly fog)
Rain, snow, sleet or freezing rain begin to fall
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Warm front symbol on weather map

16. Surface Observations
Meteorologists receive weather observations from stations all over the United States and the world
These are called surface observations
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17. Surface Observations Surface Observations include: Temperature
Humidity
Air Pressure
Wind Speed and Direction
Cloud Cover and Type
Precipitation Type and Amount
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18. Look at Weather Symbols
Use special codes or symbols to represent weather data on a map
Typical weather symbol
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19. Weather Symbol From which it is blowing Short barb = 5 knots
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From which it is blowing
Short barb = 5 knots
Long barb = 10 knots

20. Surface Observations
Programmed into a computer that plots the information on a map
Used by meteorologist to make weather predictions
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21. Practice Reading Weather Maps
Open to page 57 of your lab book and see if you can read a weather map.
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Resources Book- P.87-88
Student Lab Notebook -P.57

22. Response Sheet- Weather and Climate
Homework: Page 59 of your lab book.
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Student Lab Notebook -P.59