A snowfall consists of myriads of
minute ice crystals that fall to the ground in the form of frozen precipitation. The formation
of snow begins with these ice crystals in the
subfreezing strata of the middle and upper atmosphere when there is an
adequate Line supply of moisture present. At the core of every ice crystal
is a minuscule nucleus, a
(5) solid particle of matter around
which moisture condenses and freezes. Liquid water droplets
floating in the supercooled atmosphere and free ice crystals cannot coexist within the same cloud, since the
vapor pressure of ice is less than that of water. This enables
the ice crystals to rob the liquid droplets of their moisture and grow
continuously. The
process can be very rapid, quickly creating sizable ice crystals, some of which
(10) adhere to each other to create a
cluster of ice crystals or a snowflake. Simple flakes possess
a variety of beautiful forms, usually hexagonal, though the symmetrical shapes reproduced in most microscope
photography of snowflakes are not usually found in actual
snowfalls. Typically, snowflakes in actual snowfall consists of broken
fragments and
clusters of adhering ice crystals.
(15) For a snowfall to
continue once it starts, there must be a constant inflow of moisture to supply the nuclei. This moisture is
supplied by the passage of an airstream over a
water surface and its subsequent lifting
to higher regions of the atmosphere. The Pacific Ocean is the source of
moisture for most snowfalls west of the Rocky Mountains, while the Gulf of Mexico and the Atlantic Ocean
feed water vapor into the air currents over
(20) the central and eastern sections of
the United States. Other geographical features also can be the source of moisture for some
snowstorms. For example, areas adjacent to the Great Lakes experience their
own unique lake-effect storms, employing a variation of the process on a local scale. In addition,
mountainous section or rising terrain can
initiate snowfalls by the geographical
lifting of a moist airstream.
41. Which of the following questions does 42. The word “ minute” in line 1 is closest
in the author answer in the first meaning
to paragraph?
(A) tiny
(A) Why are snowflakes hexagonal? (B)
quick
(B) What
is the optimum temperature (C) clear for snow? (D)
sharp
(C) In
which months does most snow fall?
(D) How
are snowflakes formed?
43. What
is at the center of an ice crystal?
(A) A
small snowflake
(B) A
nucleus (C) A drop of water
(D) A hexagon
44. The
word “ adhere” in line 10 is closest in meaning to (A) belong
(B) relate
(C) stick
(D) speed
45. What
is the main topic of the second paragraph?
(A) How ice crystals form
(B) How
moisture affects temperature
(C) What
happens when ice crystals melt
(D) Where
the moisture to supply the nuclei comes from
46. The
word “ it” in line 15 refers to
(A) snowfall
(B) snowflake
(C) cluster
(D) moisture
47. What
is necessary for a snowfall to persist?
(A) A
decrease in the number of snowflakes
(B) Lowered
vapor pressure in ice crystals
(C) A
continuous infusion of moisture
(D) A
change in the direction of the airstream
48. How
do lake-effect snowstorms form?
(A) Water
temperature drop below freezing.
(B) Moisture
rises from a lake into the airstream.
(C) Large
quantities of wet air come off a nearby mountain.
(D) Millions
of ice crystals form on the surface of a large lake.
49. The
word “ initiate” in line 24 is closest in meaning to
(A) enhance
(B) alter
(C) increase
(D) begin
50. Which
of the following could account for the lack of snowfall in a geographical
location close to mountains and a major water source?
(A) Ground
temperatures below the freezing point (B) Too much moisture in the air
(C) Too
much wind off the mountains
(D) Atmospheric
temperatures above the freezing point.
Practice Test A – Answers
Question Number
|
Answer
|
Level of Difficulty
|
Answered Correctly
|
1
|
D
|
Medium
|
65%
|
2
|
C
|
Difficult
|
47%
|
3
|
A
|
Medium
|
74%
|
4
|
C
|
Medium
|
78%
|
5
|
D
|
Easy
|
86%
|
6
|
A
|
Difficult
|
40%
|
7
|
D
|
Medium
|
67%
|
8
|
C
|
Easy
|
88%
|
9
|
B
|
Medium
|
75%
|
10
|
B
|
Medium
|
63%
|
11
|
C
|
Easy
|
84%
|
12
|
B
|
Difficult
|
43%
|
13
|
C
|
Difficult
|
43%
|
14
|
A
|
Easy
|
82%
|
15
|
C
|
Difficult
|
45%
|
16
|
A
|
Medium
|
55%
|
17
|
D
|
Medium
|
80%
|
18
|
D
|
Difficult
|
48%
|
19
|
C
|
Easy
|
86%
|
20
|
D
|
Medium
|
75%
|
21
|
B
|
Medium
|
62%
|
22
|
B
|
Difficult
|
46%
|
23
|
D
|
Medium
|
58%
|
24
|
D
|
Medium
|
75%
|
25
|
A
|
Medium
|
71%
|
26
|
B
|
Medium
|
76%
|
26
|
A
|
Easy
|
83%
|
28
|
A
|
Easy
|
87%
|
29
|
D
|
Medium
|
57%
|
30
|
C
|
Medium
|
70%
|
31
|
B
|
Medium
|
80%
|
32
|
C
|
Difficult
|
45%
|
33
|
A
|
Medium
|
60%
|
34
|
A
|
Difficult
|
49%
|
35
|
D
|
Medium
|
58%
|
36
|
D
|
Medium
|
67%
|
37
|
C
|
Difficult
|
46%
|
38
|
D
|
Medium
|
65%
|
39
|
B
|
Medium
|
61%
|
40
|
A
|
Medium
|
68%
|
41
|
D
|
Medium
|
82%
|
42
|
A
|
Medium
|
74%
|
43
|
B
|
Medium
|
78%
|
44
|
C
|
Medium
|
69%
|
45
|
D
|
Medium
|
63%
|
46
|
A
|
Medium
|
80%
|
47
|
C
|
Medium
|
71%
|
48
|
B
|
Medium
|
71%
|
49
|
D
|
Medium
|
57%
|
50
|
D
|
Difficult
|
35%
|
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