Name ______________________
MAPPING WEATHER PATTERNS
Introduction - The weather at any given location is defined as the atmospheric conditions over a short
period of time. Predicting weather is based on the movement of air masses, frontal systems, and
pressure systems. Due to the uneven heating of the earth, areas of high and low pressure develop.
Wind moves air from areas of high pressure to areas of low pressure constantly trying to even out the
air pressure on Earth.
In this laboratory experiment you will use the information on the weather stations to construct various
field maps. Each weather variable provides incite into current and future weather. The last field map
you construct will contain several weather variables and will be used to predict the weather for certain
cities.
Objective - You will construct field maps and learn how to predict weather based on the movement of
air masses, fronts, and pressure systems.
Vocabulary
Isotherm Isobar Barometric Pressure Convergence Divergence Cyclone Anticyclone Air Mass Source Region Front Synoptic Weather Map -
Isotherms=10° intervals
A
Procedure 1.
a. On Map A, USE A PENCIL to draw Isotherms at a 10 interval (start with 30F).
b. Answer the questions below in complete sentences.
1. Describe the relationship between latitude and temperature.
2. Near which city (cities) is the temperature gradient the greatest? (recall from contour maps how
you determined which side of a hill had the greatest gradient, then look at the US map and do the
same)
3. What is the approximate temperature at the North Dakota/South Dakota border?
4. Using the front of the Earth Science Reference Tables, write out the formula for gradient below.
5. Using the gradient formula above, calculate the temperature gradient between Richmond, Virginia
and Hatteras, North Carolina. For full credit you must substitute the values into the equation above
(show work) solve the equation (fractions are not acceptable) and include the proper units.
6. Calculate the temperature gradient between Galveston and Kansas City. (same procedure as #5)
Isobars=4 mb intervals
B
Procedure 2:
a. On Map B, use a pencil to draw the 1004 mb, 1008 mb, 1012 mb, 1016 mb, 1020 mb, and 1024mb
Isobars. (hint - you will have two sets of circles, three on each side of the US when you are finished,
convert the pressures above into station model numbers for additional help)
b. Label the centers of High and Low Pressure on your map with a "L" and an "H".
c. Answer the questions below in complete sentences.
1. Near which city is the center of the low pressure system?
2. What type of weather would you expect at the center of the low?
3. Near which city is the high pressure system located?
4. What type of weather would you expect to find at the center of the high?
5. How will the barometric pressure change as you travel from Denver to Oklahoma City?
6. Calculate the air pressure gradient between Little Rock and Galveston. For full credit you must
substitute the values into the correct equation, show your work, solve the equation (fractions are not
acceptable) and include the proper units.
Example of arrow direction
C
Procedure 3
a. At each station model on Map C extend the shaft of the wind arrow and draw an arrow show the
direction the wind is blowing to. (see example)
b. Draw large arrows (cover several states) that show the general direction wind circulates around high
and low pressure systems.
c. Answer the questions below in complete sentences.
1. Describe the general surface wind pattern around the low pressure system? (2 motions) Draw three
arrows around the L to demonstrate surface winds.
L
2. Describe the general surface wind pattern around the high pressure system? (2 motions). Draw
three arrows around the H to demonstrate surface winds.
H
3. What causes wind?
4. Are the surface winds around a high pressure system convergent or divergent?
5. Are the surface winds around a low pressure system convergent or divergent?
6. What do closely space Isobars indicate on a weather map?
7. As the difference in air pressure between two adjacent weather stations increases, how will the
distance between isobars between the two cities change?
Precipitation (rain/snow)
D
Procedure 4:
a. The newspaper weather map at one time used the symbol "R" inside a station model to indicate
rain. On Map D draw a large circle around all the cites that are raining.
b. Lightly shade in pencil the area that is raining.
c. Draw a large "mT" and "cP" on the map to indicate the positions of these air masses.
d. Answer the questions in complete sentences.
1. In relation to the "mT" and "cP" air masses, where is the rain occurring?
2. Describe the differences between an "mT" air mass and a "cP" air mass.
3. Where did the "mT" and "cP" air masses most likely originate? (2 different locations)
4. Compare the characteristics of an air mass to the geographic region it formed.
5. Describe step by step how a cloud forms near a low-pressure center.
6. In the center of a low pressure center air is converging and rising, describe the vertical movement of
air in a high pressure center and what type of weather does this create.
7. If the storm system follows a typical storm track, which cities will most likely experience rain over
the next 12 to 24 hours. In what direction is the storm system moving?
Synoptic Weather Map
-combine maps B,C,DE
Procedure 5
a. Create a synoptic weather map by combining maps B, C, and D onto map E. Use different colors
and draw lightly to create a neat and readable map.
b. Using your knowledge of weather, draw in the locations of the cold and warm fronts.
Warm front-plot inbetween where the wind changes from east to south east
Cold front-plot between where the wind changes from southwest to northwest.
c. Answer the questions in complete sentences.
1. Which front has rain occurring 300 miles ahead of it?
2. Which front has rain occurring on both sides of the frontal interface?
3. What type of precipitation and clouds occur at a cold front?
4. What type of precipitation and clouds occur at a warm front?
5. Looking at the map, how does the wind direction change as the cold front passes (what is the wind
direction on each side of the cold front)
6. The arrows on the front indicate the direction it is moving, what city is most likely to have a
thunderstorm occur within the next 12 to 24 hours?
7. How does the air pressure and temperature change as a cold front passes through a city?
8. Draw a cross section of the fronts and air masses from Kansas City to Richmond.
______________________________________________________________
Kansas City
Richmond
Conclusion - Describe the temperature, air pressure, and moisture levels associated with a highpressure system and low-pressure system.
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