Name ________________________________________ Date _________ Period _____
MESO
Weather Systems Module
Finding Air Masses and Fronts
Materials
Packets of US Surface Weather Data Maps
o Map Packets should contain regional maps to cover the entire USA.
o Maps with current data are available at
http://weather.unisys.com/surface/sfc_se_inv.html
Two blank US Maps, one for temperature and one for dewpoint.
o http://www.nationalgeographic.com/xpeditions/atlas/
o http://nationalatlas.gov/natlas/Natlasstart.asp
The Station Model
As shown in the following diagram, temperature and dewpoint temperature are plotted
on the left hand side of “station models”, which depict the weather at each observing site
in the United States.
In this exercise, you will investigate a surface map by reading the temperature and
dewpoint values off of a map of station models.
Procedure
1. Using the map packet, plot the temperatures at various locations across the United
States on your national map. It is important that you keep your data evenly spaced
across the map.
2. Draw contour lines through your map, separating the map into bands of temperatures
in 10 degree increments. In other words, draw a contour that separates 60s from 70s,
and so on. Shade your contours using reds to show the warm areas and blues to show
cooler areas.
Where are the warmest areas on this map?
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Where are the coolest areas on this map?
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3. Use your second blank map and repeat steps 1 and 2 for the dewpoint temperatures.
For colors, use greens to show the moist or humid areas and browns to show the drier
areas.
Where are the most humid areas on this map?
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Where are the driest areas on this map?
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4. Compare both maps.
Are the dew points high or low in the warmest areas?
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Are the dew points high or low in the coolest areas?
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5. Using your dew point map as a reference, find areas on your temperature map that
you would consider to be "warm and dry", "warm and moist", "cool and dry", or "cool
and moist" Draw a circle around these areas and label them.
6. From what you already have learned about air mass source regions draw a dashed
line or an arrow showing where you believe this air mass must have traveled from.
Compare your results with another person or group in the class.
Who did you compare your maps with?
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Are your maps somewhat similar or completely different?
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List 3 similarities and 3 differences you see in your maps.
Similarities Differences
1. 1.
2. 2.
3. 3.
7. A front is defined as the boundary between two different air masses where one air
mass is advancing into the location occupied by another. If cold air is advancing into
warm air, the boundary is called a cold front. If warm air is advancing into cold air
the boundary is a warm front.
Take a look at the map packet. Can you find any area where an air mass appears to
be moving into another area?
Using the information above, determine if the boundary is a cold front or warm front.
Draw in the appropriate front.
8. Look at the air mass that is currently affecting our state. Where will this air mass
move next?
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9. Where is the next air mass that will affect us?
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10. What type of weather can we expect from such an air mass?
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