Chapter 8: Air Masses
Chapter 8: Air Masses
1) The air mass type most likely to form thunderstorms is
A) mA B) cT C) cA D) mP E) mT
4) An air mass from the Gulf of Mexico that moves northward over the U.S. in winter would be labeled
A) mT B) cT C) mP D) cP E) cA
6) An ideal source region of air masses should be
A) located at or near a pole
B) small
C) physically uniform
D) roughly half land, half water
E) located at or near the equator
7) The cP air-mass in North America originates in
A) the Arctic basin
B) interior Alaska and Canada
C) Siberia
D) Greenland
E) the North Atlantic
8) Most of the precipitation for the region east of the Rocky Mountains comes from
A) evaporation from soils and vegetation B) mT air masses
C) modified mP air masses D) mA air masses
9) When an area is experiencing several consecutive days of rather constant weather, it is experiencing:
A) air-mass weather
B) occluded front weather
C) cold-front weather
D) warm-front weather
E) none of these
10) Characteristics of an air mass source region include
A) high elevation
B) jet stream winds aloft
C) uniformity of temperature and moisture
D) sharp temperature contrasts
11) In North America the ______air mass forms only in the summer.
A) cP
B) mP
C) cT
D) mT
E) none of these
12) The air masses that have the greatest influence on weather conditions in the Midwestern United States are:
A) mT and cT
B) mP and cP
C) cT and cP
D) mP and mA
E) cP and mT
15) The typical amount of time it takes for an air mass to pass over a given area is on the order of a few
A) minutes B) hours C) weeks D) months E) days
16) An mP air mass is:
A) dry and cold
B) dry and warm
C) humid and warm
D) humid and cold
E) none of these
17) An air mass is often modified as it moves over the Earth's surface. This modification is largely due to
A) contact with the ground below
B) lifting along fronts
C) strong pressure gradients
D) jet streams above
E) clouds
18) The coldest and driest winter air-mass in North America is the
A) mT B) cP C) cA D) cT E) mP
20) Why are cT air masses of minor importance for the U.S.?
A) prevailing winds steer them away
B) upper level subsidence limits their formation
C) no large source region is near the U.S.
D) mountains block their approach
21) Why are maritime air masses from the north Atlantic of only limited concern for weather in the U.S.?
A) temperatures are usually mild over this region
B) question is incorrect; these air masses are very important
C) polar fronts block these air masses from the U.S.
D) prevailing winds move them away from the U.S.
E) they never cause severe storms
24) Which of the following occurs only in summer in North America?
A) cP B) mT C) mA D) mP E) cT
25) A cT air mass is:
A) warm and dry
B) warm and humid
C) cold and humid
D) cold and dry
E) none of these
26) "Lake-effect" snow is associated with the ______air mass.
A) mT
B) mP
C) cP
D) cT
E) none of these
27) The ______air mass provides much of the moisture for precipitation in the central and eastern United States.
A) cT
B) cP
C) mT
D) mP
E) none of these
28) The ______air mass may produce an occasional "northeaster" in the winter.
A) mT
B) mP
C) cP
D) cT
E) none of these
30) Which of these is not a process by which air masses are modified?
A) cooling from below
B) heating from below
C) evaporation of water
D) calm winds
E) lifting over mountains
31) An air mass is a body of air with
A) very high pressure everywhere
B) similar values of temperature and moisture in the horizontal
C) at least two frontal zones
D) equal density throughout
E) very low humidity in its lower layers