Download GEO165 LAB EXERCISE #1

GEO165 LAB EXERCISE #2
Tools of the Meteorologist Part 1: Middle Latitude Cyclones and
Anticyclones
Introduction
1. A cyclone is a region of low pressure. Air converges at the surface and
rises in a counterclockwise spiral.
2. As the air rises because the surrounding pressure decreases the air
cools, relative humidity rises and clouds and precipitation result.
3. Middle latitude cyclones are intimately connected to the jet stream
flowing rapidly above the low. The Bergen (Norwegian) School of
meteorology in the early 20th century developed the cyclone model, but
because upper air data were not yet available did not complete the model.
In the 1940’s and 1950’s the Chicago School of meteorology worked out
how the jet was related to the development and life cycle of the low.
4. An anticyclone is a region of high pressure. Air diverges at the surface,
first sinking from above in a clockwise spiral. Near the center of an
anticyclone winds are light and variable to calm and may not seem to make
sense. Farther from the center winds are consistent with the isobar
pattern.
5. Unlike a cyclone an anticyclone is an air mass. Over a large area the air is
fairly uniform in temperature and moisture, the anticyclone having
acquired this from its source region.
6. Anticyclones (air masses) can be warm, cold, moist or dry. See the class
website for a fuller description.
Maps for Lab #2
21 MAR 2003 – MID LATITUDE CYCLONE
19 JAN 1994 – Ca ANTICYCLONE
Assignment
1. Analyze both maps using a 2mb contour interval.
Note the data now consists of more than only pressure values, each station now has several numbers
surrounding it. Refer to the class website for the station model key.
2. Create 3d surface graphs of each pressure pattern using the MS
Excel data sheet.
DPlot instructions:
You are to create and save 2 - 3D surface graphs, one for the
cyclone and another for the anticyclone.
Select all values in the 3 columns for the anticyclone data.
Click on DPlot on the menu bar.
Click on “XYZSurface”
Save the graph as a jpeg file.
Select “Options” and click on “Contour Options”
Click on “View in 3D”
Set Azimuth to “76”
Set Elevation to “41”
Click on “Draw Sides”
Set Intervals to “17”
Set Lower to “1008”
Set Higher to “1042”
Click “OK”
Double Click on the title “data from lab2.xls” and create an
appropriate title that tells the viewer of the 3D Surface graph
What he/she is viewing
The date
Axis Values
When finished save the 3D surface graph.
For the middle latitude cyclone follow the same instructions but
substitute the following values
Set Azimuth to “76”
Set Elevation to “41”
Click on “Draw Sides”
Set Intervals to “13”
Set Lower to “1000”
Set Higher to “1026”
If the scale on the right has decimal numbers (it should not), go back to
contour options and be sure the “lower”, “higher”, and “interval” values
are correct.
3. Answer the questions.
NAME____________________________________________________
Lab #2 Questions
1. In general from what directions are the winds blowing on the North,
East, South, and West sides of the cyclone?
NORTH SIDE
EAST SIDE
SOUTH SIDE
WEST SIDE
2. What directions are the winds from on the North, East, South and West
sides of the anticyclone?
NORTH SIDE
EAST SIDE
SOUTH SIDE
WEST SIDE
3. What are the wind speeds and directions near the center of the
anticyclone? What does this tell you about a way to tentatively locate the
center of an anticyclone if all you have is wind data?
4. If the wind is at your back, in general in which direction is the low
pressure system (left or right)? This is the Law of Buys-Ballot.
5. On the cyclone map draw the 50oF isotherm in pencil first, then go over it
in red? On the anticyclone map draw the 0oF isotherm in pencil then go
over it is blue. What is the pattern of the isotherm east of the center
of the cyclone? What is the pattern of the isotherm west of the center
of the anticyclone?
6. When winds push warmer air into a region is it called “warm advection”.
When it is colder air invading a region is it called “cold advection”. Using
the isotherm patterns from question #5 label the warm and cold
advection areas on the two maps. Where is warm advection in relation to
the center of the cyclone and relative to the center of the anticyclone?
LAB #2
21MAR2003 00Z
MID LATITUDE CYCLONE
LAB #2
19JAN1994 12Z
ANTICYCLONE
cA Air Mass