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Mid-Latitude Cyclones
WHAT YOU SHOULD LEARN IN THIS EXERCISE: What weather is typically associated with the passage of fronts associated with a low pressure center.
Part A: Getting Started
A1. Background. Prior to completing this exercise do the following: Read Chapters 12, 13 and 14. Pay particular attention to the information in Chapter 14. Review the “Basic Weather Patterns” which can be found in Unit VI on GEODe Earth Science at the Foundations of Earth Science, 6e site of http://www.mygeoscience.com.
A2. Launch the application: Go to the Hands-On Meteorology web page: http://www.atmos.uiuc.edu/courses/atmos100/all_programs.html
Click on “Cyclone” from the Program column If you get a security warning message, click Run. This is a program from the University of Illinois and poses no threat.
A3. This program will show you typical tracks of mid-latitude cyclones. It will also show you how weather conditions may change at a single location during the passage of a cyclone.
A4. A meteogram appears in the upper right corner. A meteogram is a graph that displays temperature data on the vertical axis and the passage of time along the horizontal axis. Air temperature is in red and Dew Point temperature is in cyan. The vertical yellow line will cause the air temperature, dew point temperature and relative humidity at that given point in time to display below the graph.
A5. A compass is also displayed. The yellow line on the compass indicates the direction that the wind is blowing FROM. For example, a line pointing directly west indicates that the wind would be blowing FROM the west.
Part B: Alberta Clippers
B1. Choose “Alberta Clipper” from the pull-down menu at the top of the program.
B2. Start the Clipper on its typical path by clicking the “Start” button.
B3. Once the Clipper has reached its farthest position east, you can click on the Low and drag it along its path.
The meteogram to the right shows the conditions in Chicago, Illinois (red: temperature; blue: dew point; compass: wind direction). The yellow vertical line on the meteogram indicates conditions in Chicago as the weather system approaches and passes. The yellow line on the compass indicates the changes in wind direction in Chicago and corresponds with the passage of time on the meteogram.
B4. Position the low pressure center in eastern Minnesota. What are the weather conditions in Chicago, Illinois?
a. temperature:
b. dew point temperature:
c. wind direction (remember to use the direction the wind is coming from):
d. cloud cover/type (use your knowledge of fronts to answer this):
e. precipitation (use your knowledge of fronts to answer this):
B5. Position the low pressure center over eastern Ontario. What are the weather conditions in Chicago now?
a. temperature:
b. dew point temperature:
c. wind direction:
d. cloud cover/type:
e. precipitation:
B6. Over what location does the cyclone occlude?
Part C: Colorado Lows
B0. Click the “Reset” button.
B1. Choose “Colorado Low” from the pull-down menu at the top of the program.
B2. Start the cyclone on its typical path by clicking the “Start” button.
B3. Once the cyclone has reached its farthest position east, you can click on the Low and drag it along its path.
The meteogram to the right shows the conditions in Nashville, Tennessee
B4. Position the low pressure center in eastern Arkansas. What are the weather conditions in Nashville, Tennessee?
a. temperature:
b. dew point temperature:
c. wind direction:
d. cloud cover/type:
e. precipitation:
B5. Position the low pressure center over southern Illinois. Record the conditions in Nashville.
a. temperature:
b. dew point temperature:
c. wind direction:
d. cloud cover/type:
e. precipitation:
B6. Move the low pressure center over central Ohio and record the conditions in Nashville.
a. temperature:
b. dew point temperature:
c. wind direction:
d. cloud cover/type:
e. precipitation:
B7. Over what region does the cyclone occlude?
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