Chapter 4: Moisture and Atmospheric Stability
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
3) The buoyancy of a rising air parcel is greatly affected by
A) convergence of the parcel
B) air pressure
C) absorption of solar radiation
D) heat released if water vapor condenses
E) wind speed
4) During the process of adiabatic cooling, the temperature decreases because the air has
A) expanded to a larger volume
B) been compressed
C) lost heat to the colder air at higher altitudes
D) emitted infrared radiation
E) lost some of its water vapor
5) Adiabatic processes are only important for air
A) that is saturated
B) which is rising or sinking
C) that is stagnant
D) masses which remain near the Earth's surface
E) that is polluted
6) Natural convection and turbulence are most likely to occur when
A) temperature decreases rapidly with height
B) temperature increases with height
C) air pressure is relatively high
D) wind is nearly calm
E) relative humidity is low
7) The change of state from gas to liquid is called
A) melting
B) evaporation
C) sublimation
D) condensation
E) none of the above
8) The temperature of rising air parcels ______as they move upward.
A) decreases B) remains constant
C) increases D) may either increase or decrease
9) The relative humidity is 40% and the mixing ratio at saturation is 20 grams per kilogram. What is the actual mixing ratio?
A) 50 gm/kg
B) 80 gm/kg
C) 4 gm/kg
D) 8 gm/kg
E) none of the above
10) The most common reason why dew forms on the grass at night is that
A) more water vapor is present at night
B) pressure is greatest then
C) temperatures are coolest in the grass
D) the atmosphere cannot form clouds at night
E) more nuclei are present in the grass
11) If the air temperature remains constant, evaporating water into the air will ______the dew point and ______the relative humidity.
A) decrease, increase
B) increase, decrease
C) increase, increase
D) decrease, decrease
E) not change, increase
12) The capacity of the air to hold water vapor
A) decreases with an increase in temperature
B) increases with a decrease in temperature
C) increases with an increase in temperature
D) increases with an increase in pressure
13) ______results in the release of about 600 calories of latent heat per gram.
A) Sublimation
B) Evaporation
C) Condensation
D) Melting
E) none of the above
14) The gas most responsible for atmospheric processes is
A) water vapor
B) hydrogen
C) oxygen
D) nitrogen
E) carbon dioxide
15) The vertical motions that occur when the air is unstable are termed
A) cyclonic
B) convection
C) convergence
D) subsidence
E) geostrophic
16) Sinking or subsiding air cannot form clouds due to the
A) loss of particulates
B) removal of water vapor
C) warming temperatures
D) release of latent heat
E) formation of unstable layers
17) The property which primarily controls how much water can be present as a gas is
A) number of particulates present
B) amount of dry air gases present
C) availability of latent heat
D) temperature of the air
E) water's specific heat
18) The atmosphere is most unstable when the temperature of the air ______with height.
A) increases slightly
B) is uniform
C) decreases slightly
D) drops rapidly
E) increases rapidly
19) If air at sea level with a temperature of 27degreeC is forced up a mountain slope and the air's dew point at the condensation level is 14degreeC, at what elevation will condensation begin?
A) 1300 meters
B) 2600 meters
C) 2700 meters
D) 1400 meters
E) none of these
20) As the temperature of air is reduced to its dew point, which of these is most likely to occur?
A) condensation
B) melting
C) supercooling
D) evaporation
E) freezing
22) The most important process of cloud formation in the atmosphere is:
A) cooling by compression of air
B) radiation cooling
C) cooling by contact with a cold surface
D) cooling by release of latent heat of vaporization
E) cooling by expansion of air
23) During a clear, relatively calm day, the relative humidity will tend to ______from sunrise to early afternoon.
A) decrease B) increase C) remain nearly steady
24) Which of the following would not be associated with stable atmospheric conditions?
A) dreary overcast with light drizzle
B) afternoon thundershowers
C) temperature inversion
D) widespread fog
E) buildup of pollutants
25) As liquid water is evaporated into the atmosphere, heat energy is
A) released by the evaporating water
B) absorbed by the surrounding air
C) given off by the water vapor
D) absorbed by the remaining liquid
E) absorbed by the evaporating water
26) Evaporation is a process which tends to keep temperatures cooler where it occurs. This is because evaporation
A) reduces the absorption of solar energy
B) increases the reflection of solar energy
C) increases the specific heat
D) increases the outgoing radiation
E) uses energy to change the phase of water instead of warming it
27) Relative humidity indicates the
A) nearness to saturation for the air
B) actual amount of water in the air
C) chance of cloud formation
D) probability of precipitation
E) chance for evaporation of water
31) Why does a rising air parcel cool off?
A) it expands
B) it is unstable
C) it loses energy by radiation
D) it loses heat to its surroundings
E) its relative humidity is less than 100%
32) Which of these pairs of processes, working together, will make the atmosphere most unstable?
A) cool the surface and warm the air aloft
B) warm the surface and warm the air aloft
C) warm the surface and cool the air aloft
D) cool the surface and cool the air aloft
33) An adiabatic process is one in which the
A) temperature remains constant
B) work done is zero
C) heat exchanged with the surroundings is zero
D) pressure on the air parcel remains constant
E) altitude of the air parcel remains constant
34) When water vapor condenses, the heat involved
A) is released to the nearby air
B) is absorbed from the Sun
C) is absorbed from the surrounding air
D) is retained by the drop that forms
E) is absorbed by the water vapor
36) A convergence of winds near the surface is associated with cloud production because it
A) increases the wind speed
B) creates a vortex or spiral pattern
C) increases the dew point
D) forces the air to rise
E) increases the lapse rate
39) The dew point is the temperature at which:
A) water in the liquid state changes to vapor
B) water vapor condenses to a liquid
C) cumulus clouds change to cumulonimbus clouds
D) hailstones are formed
E) none of these
41) When the dry and wet bulb temperatures measured by a psychrometer are equal, all but one of the following is true. Which one is false?
A) dew point is equal to the dry bulb
B) the air is saturated
C) relative humidity is 100%
D) a rise in temperature would cause condensation
E) water vapor content is a maximum
43) The two changes of state that are the most important part of the water cycle for the atmosphere would be
A) evaporation, condensation
B) condensation, freezing
C) condensation, melting
D) melting, sublimation
E) melting, freezing
44) We are likely to have our highest relative humidity:
A) at noon
B) about sunrise
C) about midnight
D) during mid-afternoon
E) none of these
48) The heat released when water vapor condenses to form a cloud or when liquid droplets freeze in a cloud
A) helps the cloud to rise higher
B) evaporates more water
C) makes the air heavier
D) cools off the cloud
E) adds water to the cloud
50) The stability of the air layer close to the Earth's surface can vary markedly. Much of this variation is caused by
A) changes in the number of particulates
B) changes in wind speed
C) changes in pressure
D) changes in heating or cooling of the surface
E) changes in wind direction
52) Relative humidity depends on the water vapor present in the air and the
A) altitude
B) latitude
C) temperature
D) dew point
E) pressure
54) When using a psychrometer, if the two temperatures read nearly the same you can conclude that:
A) your instrument reading is accurate
B) the dew point temperature is very low
C) a change in temperature is likely
D) the air has a high relative humidity
E) none of the above
55) A parcel of air has a temperature of 0degreeC as it crosses a mountain range at 3000 meters. If it descends, what will its temperature be when it reaches sea level?
A) 40degreeC
B) 30degreeC
C) 0degreeC
D) 15degreeC
E) none of these