Name:________________________________________________             Section:________________

Weather Map Interpretation

1.   Use the July 1, 1991 weather map (Figure 7.2) to obtain the air temperature and air pressure at each of the cities listed below.

      City (Graph Symbol)            Temperature (°F)         Pressure (mb)

      Pocatello, ID (ID)                 44                             1020.0

      Rock Springs, WY (WY)        45                             1019.7

      Denver, CO (CO)                 57                             1014.3

      Dodge City, KS (KS)              71                             1010.2

      Lake Charles, LA (LA)            77                             1014.4

2.   a. Plot the air temperature for each city on the graph below and connect the points with a smooth red line.

      b. Plot the air pressure for each city on the graph below and connect the points with a smooth blue line.

 

3.   a. What kind of front is found between Pocatello and Lake Charles?                                           COLD

      b. What direction is this front moving towards?               SOUTHEAST

      c. Based on the position of this front on the weather map,  draw the approximate position of the front on the graph in Figure 7.2 using the correct weather map symbol.

4.   a. Examine the graph of air pressure in Figure 7.2.  Where is air pressure lowest?

Dodge City

b. Why?  cold frontal uplift

5.   What kind of front stretches from Indianapolis, Indiana northwestward to Minneapolis, Minnesota on the July 1, 1991 map (Figure 7.2)? WARM

 

6.   Note the areas of precipitation on the Gulf Coast of Florida, over Lake Superior, and Hudson Bay, Saskatchewan (Letter N) on the July 4, 1991 weather map (Figure 7.4).  What were the likely uplift mechanisms that caused precipitation (gray shading) at these three locations?

              Location                              Uplift Mechanism

     Gulf Coast of Florida             CONVECTIVE

     Lake Superior                         CONVERGENCE

     Hudson Bay (Letter N)           FRONTAL

7.   Use the January 3, 1988 (Figure 7.5) and July 3, 1991 (Figure 7.3) weather maps to fill in the table below.

                                                    Air                         Dew                        Air

      Station / Map                 Temperature                 Point                      Mass

   Bismarck, ND 1/3/88           8                          -9                          cP

   Miami, FL 1/3/88                74                          70                          mT

   Astoria, OR 1/3/88            36                          36                          mP

   Miami, FL 7/3/91                80                          76                          mT

   Astoria, OR 7/3/91            67                          60                          mP

   Bismarck, ND 7/3/91         60                          54                          cP

8.   Using your knowledge of air masses and the data collected for question 10 as a guide, compare and contrast the temperature and humidity characteristics of cP, mP, and mT air masses during the summer and winter.

a.   cP air mass      Winter: COLD AND DRY, Summer: MILD AND DRY

 

b. mP air mass       Winter: MILD AND WET, Summer: COOL AND HUMID

 

c. mT air mass       Winter: WARM AND WET, Summer: WARM AND HUMID

 

9.   Why are air masses usually warmer and more humid in the summer than in the winter?

WITH MORE HEAT ENERGY AVAILABLE IN SUMMER, A GREATER AMOUNT CAN BE USED TO EVAPORATE WATER. ALSO, THUNDERSTORMS ARE MORE FREQUENT, AND TRANSPIRATION FROM PLANT GROWTH IS GREATER, DURING SUMMER.

 

10. a.   Which air mass has more water vapor in it, mP or mT?   mT

b.   Why? THE HIGHER DRY AIR TEMPERATURES ALLOW GREATER HUMIDITY CONTENT

 

 

11. a.   Which city, Miami or Astoria had the higher relative humidity in January? ASTORIA

b.   How do you know? EUREKA HAD NO DIFFERENCE BETWEEN DRY AND DEW POINT TEMPERATURES

 

12. a.   Where will it feel more humid, Miami or Astoria?  ASTORIA IN JANUARY, MIAMI IN JULY

b. How do you know? SMALLER DIFFERENCES BETWEEN DRY AND DEW POINT TEMPERATURES FEEL MORE HUMID

 

13. Intense cyclones are characterized by their strong pressure gradients, high winds and severe weather, be this blizzard conditions during the winter or thunderstorm and tornado conditions during the spring and summer.

a.   During which season (summer or winter) are the surface cyclones most intensely developed? WINTER

 

b.   Why is this so? LARGER THERMAL GRADIENTS CREATE GREATER PRESSURE IMBALANCES

 

c.   If intensity is related to the pressure gradient across the system, how can you determine the intensity of a cyclone from a weather map? CLOSER ISOBARS AND LARGER TEMPERATURE DIFFERENCES BETWEEN LATITUDES IN WINTER

14. On January 3, 1988 (Figure 7.5) a cold front stretching from central Canada to Pierre, SD is moving toward the southeast.

15. Bismarck, ND lies to the west of the front and Minneapolis, MN to the southeast. Collect the following weather data from the January 3, 1988 map (Figure 7.5) for these two cities located on opposite sides of the front.

 

Weather Element

Bismarck

Minneapolis

Air Temperature

8

12

Dew Point Temperature

-9

8

Wind Direction

NW

SW

Wind Speed

20

10

Sky Cover

CLEAR

OVERCAST

Air Pressure

1021.6

1018.5

 

16. In 24 hours the front is expected to pass Minneapolis, MN.  Examine the conditions on both sides of the front as represented in the data compiled for question 18. Predict what will happen to the air temperature (increase or decrease), dew point temperature (increase or decrease), sky cover (increase or decrease), and change in wind direction as the front moves through Minneapolis. BECOMING NW AND STRONGER

 17.      Collect the following data from the January 4, 1988 map (Figure 7.6).

 

Weather Element

Minneapolis

Trend over the past 24 hours (e.g. increase or decrease)

Air Temperature

-6

DECREASE

Dew Point Temperature

-16

DECREASE

Wind Direction

NW

W, THEN NW

Wind Speed

20

INCREASE

Sky Cover

MOSTLY CLEAR

DECREASE

Air Pressure

1025.6

INCREASE

 

21. Compare the actual conditions to your prediction. actual conditions conform with the predictions