Copyright 2008 Kendall/Hunt Publishing Company - CAMP

Name: _____________________________________________ Class: ____________ Date: ____________
PGF = Pressure Gradient Force
CF = Coriolis Force
FR = Frictional Force
GR = Gravitational Force
Exercise 7.1 Forces in the Atmosphere
Place letters on the blanks in each statement to make the statement correct.
1. The _________________ is zero at the equator and increases with latitude.
2. The _________________ acts to accelerate air horizontally from rest.
3. The _________________ can change the direction air moves, but not its speed.
4. The _________________ is strongest near the earth’s surface and decreases in importance at higher altitudes.
5. The strength of the _________________ is visualized on a surface map by isobars.
6. In the Northern Hemisphere, the _________________ always acts opposite the direction of air motion, but the
_________________ always acts to the right of the air motion.
7. For weather applications, the magnitude of the _________________ acting on any air parcel can be considered
constant throughout the troposphere.
8. The _________________ acts to reduce the speed of air.
9. Except for very close to the surface, _________________ acts primarily through the mixing of parcels of air
moving at different speeds.
10. The _________________ is an apparent force associated with the rotation of the Earth.
11. The _________________ is always directed toward lower values of pressure.
Copyright 2008 Kendall/Hunt Publishing Company
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Copyright 2008 Kendall/Hunt Publishing Company

Name: _____________________________________________ Class: ____________ Date: ____________
Exercise 7.2 The Horizontal Pressure Gradient Force
1. At each of the large black dots on the map above, draw an arrow emerging from the dot to indicate the direction
of the pressure gradient force (PGF). Adjust the length of your arrows so that a long arrow indicates a
relatively strong PGF and a short arrow indicates a relatively weak PGF. Arizona has been done for you.
2. What is the average value of the pressure gradient between the high-pressure center on the West Coast
(1033 mb) and the low-pressure center in Colorado (988 mb)? Assume the distance between these two points
is approximately 1500 km.
3. Salt Lake City, in northern Utah about halfway between the high and low, is approximately 20 kilometers in
diameter. What is the approximate pressure change (in mb/km) across Salt Lake City?
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Copyright 2008 Kendall/Hunt Publishing Company

Name: _____________________________________________ Class: ____________ Date: ____________
Exercise 7.3 The Geostrophic Wind
Assume that the flow represented on the 500 mb map above is in geostrophic balance.
1. Draw an arrow showing the speed and direction of the geostrophic wind at each of the four points indicated
on the map. The “tail” of each arrow should be at the point and the length of the arrow should be proportional
to wind speed.
2. Draw a second arrow at each point that represents the pressure gradient force (PGF). Again, the tail of the
arrow should be at each point, the arrow should point in the direction the force acts, and the length of the
arrow should represent the relative strength of the PGF. Label the arrow “PGF.”
3. Do the same as in (2), but for the Coriolis Force. Label the arrow “CF.”
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Copyright 2008 Kendall/Hunt Publishing Company

Name: _____________________________________________ Class: ____________ Date: ____________
Exercise 7.4 Fronts and the Jetstream
1. The maps on the left are surface maps depicting positions of frontal boundaries and low- and high-pressure
centers. The maps on the right depict wind speed at 300 mb, with the light shading indicating winds exceeding
70 knots and the dark shading indicating winds exceeding 100 knots. Match the surface map with the jet
stream.
Map A matches Map _________________
Map B matches Map _________________
Map C matches Map _________________
2. How did you determine the matching?
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Copyright 2008 Kendall/Hunt Publishing Company