Homework 5

 

This assignment is due on Wednesday, October 12 at the beginning of the lecture.

  1. Fill in the blanks in this paragraph: "The ITCZ is a region of _______________ (sinking or rising?) motion in the atmosphere. It is characterized by _______________ (frequent or infrequent?) thunderstorms, and is typically found __________________ (far from or near?) the equator, typically in the _______________ (summer or winter?) hemisphere. At the _____________ (surface or tropopause?), outflow from the ITCZ flows poleward, and is deflected by __________________ (friction, the pressure gradient force, or the coriolis force?) into the ___________________ (polar jet or subtropical jet?). At these latitudes, air ___________ (rises or sinks?) into the subtropical _____________ (high or low?) pressure belts, which are regions of great ___________________ (deserts or rain forests?). These motions of the atmosphere constitute the ____________ (Hadley, Ferrell or Polar) Cell."
  2. Fill in the blanks in this paragraph: "The polar regions are characterized by ______________________ (high or low?) pressure. At the surface, winds flow from the polar latitudes and ______________________ (converge or diverge?) with winds flowing poleward from the subtropical highs at the polar front, which is a region of ______________________ (rising or sinking?) motion. According to the Thermal Wind Relationship, directly above the polar front we should find the ______________________ (subtropical or polar?) jet stream. This jet stream is found just below the ______________________ (stratopause, tropopause or mesopause?) and occurs because of differences in thickness on the poleward and equatorward sides of the polar front. Equatorward of the polar front, thicknesses are ______________________ (small or large?), whereas poleward of the polar front, thicknesses are ______________________ (small or large?). Aloft, these differences in thickness result in ______________________ (small or large?) pressure gradient forces. Since this jet stream ______________________ (is or is not?) geostrophic, the winds in the jet stream blow ______________________ (parallel to or across) contours, with colder temperatures to the ______________________ (right or left?) of the flow in the Northern Hemisphere."
  3. What are "trade winds"? (Tell me where you find them on earth, at what level you find them, what direction these winds are blowing, etc.)
  4. What are the winds like in the "horse latitudes"? Where are the "horse latitudes"?
  5. If the rotation of the earth reversed, which way would the subtropical jet stream flow? Why?
  6. Follow these instructions (or just go directly to this web page):
    • Go to the textbook's website at http://info.brookscole.com/ackerman. (You will need to be using Internet Explorer--not Firefox or any other browser--for this to work.)
    • Click on the link that reads "Student Book Companion Site" (the link is red and on the right side of the window).
    • On the dropdown menu for "Select a chapter", pick Chapter 7--"Global Scale Winds".
    • Along the left side of the wind, click on "Applets".
    • Finally, click on "Making a Jet Stream".

    Once you have loaded the applet, use it to answer the following questions about the Thermal Wind Relationship:

    1. As you change the temperature gradient what happens to the maximum wind speed?
    2. What does this simple model predict about the global winds if the temperature was uniform across the globe?
    3. About how high up are the strongest winds in the Midlatitude Jet Stream?
    4. At about what latitude would you find the Midlatitude Jet Stream?
  7. In a cold air mass, the 500mb surface is ______________ (closer to or farther from?) the ground than it is in a warm air mass? Why?
  8. Explain the requirements for a geographic region to serve as a "source region" for an air mass?
  9. Why is there no such thing as a mA air mass?