Review Questions for Quiz #4
 

• atmospheric pressure
1. How does atmospheric pressure change with altitude?
2. What is the difference between station pressure and sea level pressure?
3. What is a typical station pressure for Tucson?
4. Typically, how much does this vary over the course of a day.
5. What is an isobar?
• Ideal gas law
1. If the pressure of the gas in a balloon is held constant, then how will the density change with the temperature of the gas?
• Pressure gradient
1. If the distance from Denver to Minneapolis is about 1000 km, using the sea level pressure map  http://www.atmo.arizona.edu/spring00/ATMO171-flittner/130999_sfcP.gif  what is the horizontal pressure gradient between Denver and Minneapolis?
• Surface pressure maps and pressure surface maps
1. What is an isobar?
2. Look at the 500 mb map at  http://www.atmo.arizona.edu/spring00/ATMO171-flittner/130999_500H.gif  (which is the same as the hand-out) and tell me what is the 500 mb height over Tucson (you'll have to estimate it).  Explain what this number means (This is the more important part of the question).
3. What is the pressure at a point on the 500 mb map directly over Chicago?
• General characteristics of High and Low pressure regions
1. If the forecast for the next several days is for Tucson to be under the influence of high pressure, what sort of weather would you expect?
2. If the air over the state of Oklahoma is gradual rising, would you expect to find high pressure or low pressure at the surface?
• Forces that affect the movement of air
1. Generally, the vertical pressure gradient is balanced by what force?  When these 2 forces are equal in size, but in opposite directions, meteorologist call it _____ equilibrium.
2. On the 500 mb map mentioned above, identify regions where the pressure gradient force (PGF) is larger and where it is smaller.  Pick a few points on the map, say in midwest, in northern Georgia on the 5880 contour, and south of Florida on the 5880 contour, and draw an arrow in the direction of the PGF.
3. Know the characteristics of the Coriolis Force (See the outline on forces )
4. How does the frictional force change with altitude? Then how should the wind change with altitude?  Would you expect there to be shear?
• Winds on an upper level map and a sea level pressure map (Some of these are the same question, just different was of asking the same question.)
1. For the points used in question #2 of the Forces section above, draw the direction of the wind, and the direction of the Coriolis force.
2. On our well used 500 mb map, identify regions where the winds would be greatest and where they would be the least.
3. Again, using the 500 mb map, are there any regions that where the PGF would be equal to the CF?  For a hint, remember what was said about geostrophic balance.  This will clue you into looking for regions where the contours are straight (no curvature).
4. Use the 500 mb map one last time to now estimate what would be the direction of the wind at the surface at the points used in #2 of the Forces section and #1 of this section.
5. To really make sure you have an understanding of the relation between forces and winds do the following for upper level winds;
1. Draw a closed low pressure (concentric circles with the lowest pressure at the middle) and draw the direction of the wind, PGF, & CF at two points (i.e. the top, left side of the circle) in the Northern Hemisphere.
2. Now do the same for a high pressure in the Northern Hemisphere.
3. Now the same for a low pressure in the Southern Hemisphere.  Remember the thought experiment we did in class with the balloon initially at rest and then releasing it to move under the influence of the PGF & CF.
• Relationship between observed wind and atmospheric pressure
1. The Dutchman, Buys-Ballot, noted the following relationship in the Northern Hemisphere between the direction of the wind and the atmospheric pressure: When the wind is at your back, then lower pressure is ___ of you.
1. to the left
2. to the right
3. directly behind
4. directly in front
2. For tonight the forecast is for a low pressure region to move to the south of Tucson, at which time you would expect the wind to be from the ___.
   1. south
   2. north
   3. east
   4. west