Chapter 11 Questions for Review 1. If an area is described as a “good air mass source region”, what information can you give about it? a. A “good air mass source region” or “ideal source regions” are usually those areas dominated by surface high pressure. They include the ice and snow covered artic plains in winter and subtropical oceans in summer. 2. It is summer. What type of afternoon weather would you expect from an air mass designated as mT? Explain. a. In summer, the weather we could expect from mT air mass would be warm, moist and usually unstable. It would be warm because tropical (T) air masses form in a warm tropical region. It would be moist because maritime (m) air masses originate over water. 3. Why is continental polar air not welcome to the Central Plains in winter and yet very welcome in summer? a. A summertime continental polar (cP) air is welcome in the Central Plains because is usually brings relief from the oppressive heat in the central states as cooler air lowers the air temperature to more comfortable levels. In winter, however, a continental polar (cP) can bring bitter cold winter weather. 4. Explain why the central United States is not a good air mass source region. a. The central United States is not a good air mass source region because it is located in the middle latitude. Middle latitudes, where surface temperatures and moisture characteristics vary considerably, are not good source regions. 5. Why do air temperatures tend to be a little higher on the eastern side of the Appalachian Mountains than on the western side, even though the same winter cP or cA air mass dominates both areas? a. Air rides up and over the lower Appalachian Mountains. Turbulent mixing and compressional heating increase the air temperatures on the downwind side. Consequently, cities located to the east of the Appalachian Mountains usually do not experience temperatures as low as those on the west side. 6. Explain how the airflow aloft regulates the movement of air masses. a. Since the air mass itself is generally uniform with low winds, its movement is almost entirely dictated by air movements aloft, which push on the air mass moving it around. 7. List the temperature and moisture characteristics of each of the major air mass types. a. cA - Continental Artic - Extremely cold, dry stable; forms over an ice and snow-covered surface b. cP - Continental Polar - cold, dry, stable
c. cT - Continental Tropical - hot, dry, stable air aloft; unstable surface air d. mP - Maritime Polar - cool, moist, unstable e. mT - warm, moist; usually unstable 8. What are lake-effect snows and how do they form? On which side of a lake do they typically occur? a.
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