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Chapter 25 Driving Forces of Weather
25.1 Atmospheric Moisture
1) Temperature in the air is increased by the process of
A) moisture condensation.
B) contact with cold surfaces.
C) moisture evaporation.
D) all of the above
Answer: A
2) Temperature in the air is decreased by the process of
A) moisture condensation.
B) moisture evaporation.
C) contact with warm surfaces.
D) solar radiation.
Answer: B
3) The changing of a substance from a liquid into a vapor or gas is called
A) condensation.
B) evaporation.
C) dew point.
D) saturation point.
Answer: B
4) As rising air cools, its ability to hold water vapor decreases so the
A) relative humidity of the rising air decreases.

B) adiabatic rate stabilizes.
C) air becomes more wet.
D) relative humidity of the rising air increases.
Answer: D
5) Saturation and condensation are more likely to occur in
A) warm air than in cool air.
B) air with a low relative humidity
C) cool air than in warm air.
D) an adiabatic air mass.
Answer: C
6) When water changes from a liquid to a vapor, it
A) loses energy.
B) gives off energy.
C) gains energy.
D) radiates energy.
Answer: C
7) The changing of a vapor into a liquid is called
A) condensation.
B) evaporation.
C) dew point.
D) saturation point.
Answer: A

8) When water changes from a vapor phase to a liquid phase, it
A) loses energy.
B) gives off energy.
C) gains energy.
D) radiates energy.
Answer: A
9) When water changes from solid ice to a liquid, it
A) loses energy.
B) gives off energy.
C) gains energy.
D) radiates energy.
Answer: C
10) When liquid water freezes, it
A) loses energy.
B) gives off energy.
C) gains energy.
D) radiates energy.
Answer: A
11) The amount of water vapor the air can hold depends on air temperature. At higher
temperatures the air
A) holds less water vapor.
B) can hold more water vapor.

C) is saturated.
D) holds water vapor at its dew point.
Answer: B
12) The temperature to which air must be cooled for saturation to occur is called
A) relative humidity.
B) its dew point.
C) precipitation.
D) its condensation point.
Answer: B
13) The limit at which the air contains as much moisture as it can hold for a given temperature is
called
A) the dew point.
B) saturation.
C) the evaporation point.
D) sublimation point.
Answer: B
14) We feel uncomfortably warm on a muggy day because water molecules are
A) evaporating from moist bodies.
B) condensing on our bodies.
C) preventing the evaporation from our moist bodies.
D) jostling about.
Answer: B

15) We are warmed by condensation because water molecules in the air that strike our bodies
A) transfer some of their kinetic energy to us.
B) gain kinetic energy as they change state.
C) form an insulating layer on our bodies.
D) none of these
Answer: A
16) Whenever water condenses,
A) heat is absorbed.
B) heat is released.
C) frost forms.
D) temperature drops.
Answer: A
17) Evaporation of raindrops in the atmosphere
A) warms the air.
B) cools the air.
C) does not happen, raindrops always reach Earth's surface.
D) is greatest above polar ice caps.
Answer: B
18) Whenever water evaporates,
A) heat is absorbed.
B) heat is released.
C) temperature rises.

D) clouds form.
Answer: B
19) The evaporation of raindrops in the atmosphere
A) cleans the air.
B) warms the air.
C) cools the air.
D) occurs only above tropical waters.
Answer: C
20) As air temperature decreases, relative humidity
A) drops.
B) stays the same.
C) decreases.
D) increases.
Answer: D
21) Air becomes saturated when its temperature
A) falls to a point where water vapor molecules evaporate.
B) rises to a point where water vapor molecules condense.
C) rises to a point where water vapor molecules evaporate.
D) falls to a point where water vapor molecules condense.
Answer: D
22) Precipitation is produced by
A) a rising air mass.

B) a descending air mass.
C) water vapor in the air that condenses to make clouds then falls as liquid water or ice.
D) all of the above.
Answer: C
23) Warm, moist air blowing over cold water can result in
A) adiabatic cooling.
B) a dry adiabatic rate.
C) fog.
D) orographic lifting.
Answer: C
24) During the summer months, the Gulf of Mexico is generally
A) cool along the coast.
B) very hot and very humid.
C) hot and dry.
D) none of the above.
Answer: B
25) Water vapor in the air can condense when the air
A) cools above its dew point temperature.
B) temperature increases.
C) temperature drops below its dew point temperature.
D) none of the above.
Answer: C

26) Saturation and condensation are more likely to occur on a
A) cold day.
B) warm day.
C) windy day.
D) balmy day.
Answer: A
27) As air temperature decreases, relative humidity
A) increases.
B) decreases.
C) stays the same.
D) becomes colder.
Answer: A
28) If the relative humidity is 50%, what happens when the temperature drops and the mass of
water in the air stays the same?
A) Relative humidity drops.
B) Relative humidity rises.
C) Relative humidity stays the same.
D) Outcome depends on the temperature of the air.
Answer: B
29) What happens if nearly saturated air experiences a quick, significant temperature drop?
A) Relative humidity drops.
B) Relative humidity rises.

C) Condensation occurs.
D) Outcome depends on the temperature of the air.
Answer: C
30) Which of the following is not an example of condensation at Earth's surface?
A) Clouds
B) Dew
C) Frost
D) Fog
Answer: A
31) Why does dew form on the ground during clear, calm summer nights?
Answer: The ground and objects on the ground are net radiators of terrestrial radiation at night
(when solar input is absent), so are often cooler than the surrounding air. As air comes into
contact with these cold surfaces, it cools. As the air cools below its dew point, water vapor
condenses onto the nearest available surface, the ground or a twig or blade of grass.
32) Is evaporation greater over warm ocean water or cold ocean water?
Answer: The faster moving H2O molecules in warm water more readily evaporate, so
evaporation is greater above oceans in warm regions (warm air holds more moisture than cool
air). Less evaporation in polar waters is one reason why there is little snowfall in the polar
regions.
33) If water vapor content is held constant as air temperature decreases, does relative humidity
increase, decrease, or stay the same? Explain.
Answer: With a constant water vapor content, cooling the air causes the relative humidity to
increase, whereas warming the air causes the relative humidity to decrease. In cool air, relative
humidity increases because the air is approaching saturation. Remember, air with a high relative
humidity is not necessarily holding a great deal of water vapor, it is simply holding close to its
capacity for water vapor.

34) When water vapor condenses to liquid water, is thermal energy absorbed or released?
Answer: Thermal energy is released by the condensation of water, so condensation is a warming
process (the opposite of evaporation).
35) What happens to the water vapor in saturated air as the air cools?
Answer: Because lower air temperatures are characterized by slower-moving molecules, the
water vapor condenses. This is because slower-moving molecules are more likely to stick to one
another when colliding than faster-moving H20 molecules.
36) Why does a July day in the Gulf of Mexico generally feel appreciably hotter than a July day
in Arizona?
Answer: Greater water content in the air around the Gulf of Mexico makes for more humidity.
Arizona, in contrast, has no large body of water to wet the air. Even though both regions may
have the same temperature, the prohibiting effect of humidity on bodily evaporation finds one
feeling considerably warmer in the Gulf States.
25.2 Weather Variables
1) As air rises, it
A) compresses and warms.
B) compresses and cools.
C) expands and warms.
D) expands and cools.
Answer: D
2) An adiabatic process occurs when
A) no thermal energy enters or leaves the system.
B) thermal energy leaving a system is greater than thermal energy entering a system.
C) thermal energy leaving a system is less than thermal energy entering a system.

D) none of these
Answer: A
3) As an air parcel moves up the side of a mountain, it
A) expands and cools.
B) expands and warms.
C) compresses and cools.
D) compresses and warms.
Answer: A
4) Warm air rises and cools as it expands. Warm air will continue to rise as long as it is
A) denser than the surrounding air.
B) warmer and less dense than the surrounding air.
C) warmer and less dense than the air above.
D) snowing.
Answer: B
5) As an air parcel expands and cools, or compresses and warms, with no interchange of heat
with its surroundings, the situation is called
A) temperature equilibrium.
B) an adiabatic process.
C) stable equilibrium.
D) lapse rate.
Answer: B
6) Any object that is warmer than its surroundings will

A) absorb heat.
B) emit radiation.
C) reflect heat.
D) become denser.
Answer: B
7) If a volume of air is warmed, it expands. If a volume of air expands, it
A) warms.
B) cools.
C) neither warms nor cools.
Answer: B
8) When a volume of air is compressed, its temperature
A) increases.
B) decreases.
C) neither increases nor decreases.
Answer: A
9) The wind blows in response to
A) pressure differences.
B) Earth's rotation.
C) temperature differences.
D) pressure and temperature differences and Earth's rotation.
E) all of these
Answer: D

10) As rising air cools,
A) its capacity for containing water vapor decreases.
B) the relative humidity of the rising air increases.
C) none of these occurs.
D) relative humidity increases as the air becomes saturated.
Answer: D
11) Clouds inhibit the outflow of terrestrial radiation. This acts to
A) insulate Earth's surface temperature.
B) warm Earth's surface temperature at night.
C) cool Earth's surface temperature during the day.
D) insulate Earth's surface temperature, keeping it warmer at night and cooler in the day.
Answer: D
12) As air flows up the side of a mountain, the air pressure
A) increases.
B) decreases.
C) gets warmer.
D) gets colder.
Answer: B
13) Warm air rises and cool air sinks. So when an air parcel rises it becomes
A) cooler.
B) warmer.
C) more stable.

D) less stable.
Answer: A
14) Which air mass has greater air pressure?
A) Warm air.
B) Cold air.
C) Adiabatic air.
D) Expanding air.
Answer: A
15) When warm air is above cooler air it is called
A) stable.
B) unstable.
C) a temperature inversion.
D) a Chinook.
Answer: C
16) As air rises, it
A) compresses and warms.
B) compresses and cools.
C) expands and warms.
D) expands and cools.
Answer: D
17) Heat can be added to air by solar radiation, moisture
A) condensation, or contact with warm ground.

B) evaporation, or contact with warm ground.
C) condensation, or contact with cool ground.
D) evaporation, or contact with warm ground.
Answer: A
18) A rising parcel of air continues to rise as long as
A) the wind is blowing.
B) it is warmer and less dense than the surrounding air.
C) the temperature is inverted.
D) it is cooler and denser than the surrounding air.
Answer: B
19) Which of the following is an example of adiabatic warming?
A) Cyclone.
B) Chinook.
C) Drought.
D) Tornado.
Answer: B
20) Air is considered unstable when it
A) continues to rise because it is warmer than surrounding air.
B) behaves unpredictably.
C) warms as it descends.
D) cools as it rises.
Answer: A

21) Air moves from
A) a region of low pressure to a region of high pressure.
B) a region of high pressure to a region of low pressure.
C) a region of stability to a region of instability.
D) a cold front to a warm front.
Answer: B
22) As air rises, it expands. It expands because it moves to
A) a region of higher air pressure.
B) a region of lower air pressure.
C) an area of greater humidity.
D) an area of cooler air temperature.
Answer: B
23) How are air convection cycles generated?
Answer: Warm air rises, expands and cools. After the air cools, it sinks to occupy the volume left
vacant by the rising warm air. This starts and maintains a convection cycle.
24) What is a temperature inversion?
Answer: A temperature inversion is the condition occurring when the upper regions of the air (or
atmosphere) are warmer than the lower regions. The air above acts like a blanket on the air
below and does not allow the air to mix. A temperature inversion traps smog and other thermal
pollutants.
25) The Chinook wind is a warm, dry wind that descends the eastern slope of the Rocky
Mountains. What makes these winds so warm and dry?
Answer: As air rises on the windward side, it expands and cools at a dry adiabatic rate. Upon
descending the leeward side, the air is compressed and warms. If the warm air moves in aloft

above the mountain peaks, the sinking air will be even warmer on the leeward side. If clouds
form on the windward side, the descending air will be warmer and drier.
26) Is it possible for the temperature of an air mass to change if no thermal energy is added or
subtracted? Defend your answer.
Answer: Yes! Recall that temperature is proportional to pressure; if an air mass is lifted up a
mountain slope, the temperature will drop because the pressure drops. If an air mass sinks down
a slope, its temperature and pressure will go up. The latter is an example of a Chinook wind.
27) What happens to the air pressure of an air parcel as it flows up the side of a mountain?
Answer: As an air parcel flows up the side of a mountain, air pressure within the parcel decreases
because the pressure of the surrounding air decreases with altitude. This allows it to expand and
cool.
28) What is an adiabatic process?
Answer: An adiabatic process is one where no thermal energy enters or leaves a system.
29) At the same level and temperature in the atmosphere, is moist air lighter or heavier than dry
air?
Answer: Moist air is lighter! Think of the thundercloud where warm moist air continues to rise
upward until it reaches the point where it can no longer hold its moisture. Warm moist air rises
more readily than warm dry air. Note also the chemical composition of moist air and dry air. Dry
air is mainly N2 (atomic mass 28) and O2 (atomic mass 32). Moist air has N2 and O2, but it is also
diluted with H2O (atomic mass 18). Because the increased percentage of water molecules in
moist air means a decreased percentage of heavier nitrogen and oxygen molecules, moist air is
lighter than dry air.
30) Why does a drop in air pressure indicate the coming of cloudy weather and a rise in air
pressure indicate clear weather?
Answer: First of all, warm air is associated with high atmospheric pressure and cold air is
associated with low atmospheric pressure. As air rises it cools by expansion. As air sinks it
warms by compression. As air sinks and warms, its capacity for holding water vapor increases.
Because more water vapor molecules are required to saturate a warmer air parcel, sinking air

inhibits the formation of clouds. On the other hand, as rising air cools, its capacity for holding
water vapor decreases. Because less water vapor is required to saturate the colder air, rising air
enhances cloud formation. Cloudy skies are thus due to rising (cooling) air and low pressure,
while clear skies may be the result of sinking (warming) air and high pressure.
25.3 Cloud Development
1) An example of a convective cloud is the
A) nimbostratus.
B) cumulus.
C) cirrocumulus.
D) altostratus.
Answer: B
2) Cloud types associated with stable air include
A) cumulus and cumulonimbus.
B) cirrostratus, altostratus, and stratus.
C) cirrostratus, altocumulus, and altostratus.
D) stratocumulus, stratus, and cirrostratus.
Answer: B
3) Clouds that develop about 1000 meters above the ground are generally
A) cirrus and cirrocumulus type clouds.
B) cumulus and stratus type clouds.
C) cumulus and cirrocumulus type clouds.
D) cirrocumulus and altocumulus type clouds.
Answer: B

4) Clouds that begin to develop 6000 meters above the ground are generally
A) stratus and stratocumulus type clouds.
B) cumulus and stratus type clouds.
C) cirrus and cirrostratus type clouds.
D) cumulonimbus and altocumulus type clouds.
Answer: C
5) Clouds denoted by the prefix "alto" form
A) 4000 to 6000 meters above the ground.
B) 2000 to 6000 meters above the ground.
C) 1000 to 4000 meters above the ground.
D) 6000 meters above the ground.
Answer: B
6) Clouds occur when moist air is cooled by
A) expansion when it rises.
B) compression when it rises.
C) expansion when it falls.
D) compression when it falls.
Answer: A
7) Cumulus clouds generally occur in an atmospheric state of
A) stability.
B) instability.
C) cool, dry adiabatics.

D) warm, moist adiabatics.
Answer: B
8) In order to produce precipitation, an air mass must rise because rising air
A) allows water droplets more time in the cloud where they can grow in size.
B) produces downdrafts which increases the evaporation of droplets from the cloud.
C) supports the downfall of raindrops.
D) all of the above.
Answer: A
9) As cumulus clouds grow they shade the ground from the Sun. This acts to
A) slow down the heating of the ground surface.
B) dissipate cumulus cloud formation.
C) slow down convectional lifting.
D) slowly cool the ground surface, slowing convectional lifting, and dissipating cloud formation.
Answer: D
10) What generally causes clouds to form?
A) Falling relative humidity.
B) Sinking of saturated air.
C) Lifting of air.
D) Addition of water vapor.
Answer: C
11) High clouds have the prefix:
A) Nimbo-.

B) Alto-.
C) Strato-.
D) Cirro-.
Answer: D
12) Which type of cloud is also called a thunderhead?
A) Nimbus.
B) Cirrus.
C) Stratocumulus.
D) Cumulonimbus.
Answer: D
13) For rain to precipitate requires
A) condensation nuclei, updrafts, and thick clouds.
B) sufficient vertical cloud development.
C) wind.
D) droplet bombardment.
Answer: A
14) Why are there usually large spaces of blue sky between cumulus clouds?
Answer: Warm air rises and cool air sinks. As cool air sinks, the expansion of warm air beneath
it is inhibited, so we usually see isolated cumulus clouds with a great deal of blue sky between
them.
15) Why do cumulus clouds often form, disappear, and then reform in the same place?
Answer: As cumulus clouds grow, they shade the ground from the Sun, which slows surface
heating and inhibits upward convection of warm air. Without a continuous supply of rising air,

the cloud begins to dissipate. Once the cloud is gone, the ground reheats, allowing the air above
it to warm and rise. Thus convectional lifting begins again, and another cumulus cloud begins at
the same place.
16) Why is it usually necessary for an air mass to rise if it is to produce precipitation?
Answer: The production of cloud droplets into water droplets. Recall that water droplets in
clouds are so small that they evaporate before reaching the ground. Rising air allows the water
droplets more time in the cloud where they can grow in size. Once the weight of the drop
corresponds to a terminal velocity greater than the updraft speed of the rising air, the drop
descends growing larger as it falls through the moist air, yielding precipitation.
17) Does a rising moist air mass or a descending moist air mass produce precipitation? Why?
Answer: Both! Although precipitation actually falls from a descending moist air mass, the
production of rain (or snow) requires both descending and rising air or, downdrafts and updrafts.
Recall that most water droplets in clouds are so small that they evaporate before reaching the
ground. Updrafts allow the water droplets more time in the cloud where they can grow in size.
Once the weight of the drop is greater than the force of the updraft, the drop descends growing
larger as it falls through the moist air. As the drops descend, they create a downdraft which, once
created, yields precipitation.
25.4 Air Masses, Fronts, and Storms
1) Warm humid air is characteristic of a
A) maritime polar air mass.
B) continental polar air mass.
C) maritime tropical air mass.
D) continental tropical air mass.
Answer: C
2) When an air mass is pushed upward over an obstacle, it undergoes
A) convectional lifting.

B) orographic lifting.
C) adiabatic lifting.
D) frontal lifting.
Answer: B
3) An air mass with circulatory motion is called
A) convectional.
B) orographic.
C) adiabatic.
D) frontal.
Answer: A
4) Atmospheric lifting resulting from the convergence of two different air masses is called
A) convectional lifting.
B) orographic lifting.
C) adiabatic lifting.
D) frontal lifting.
Answer: D
5) Another name for the leeward slope is
A) upslope.
B) downslope.
C) rain shadow.
D) downslope and/or rainshadow.
Answer: D

6) When a cold air mass moves into a region occupied by a warm air mass, the contact zone is
called
A) a cold front.
B) a warm front.
C) a stationary front.
D) an occluded front.
Answer: A
7) When a warm air mass moves into a region occupied by a cold air mass, the contact zone is
called
A) a cold front.
B) a warm front.
C) a stationary front.
D) an occluded front.
Answer: B
8) Lower temperatures can be expected
A) behind a stationary warm front.
B) behind an advancing warm front.
C) ahead of an advancing cold front.
D) behind an advancing cold front.
Answer: D
9) Warmer temperatures can be expected
A) behind a stationary front.
B) behind an advancing warm front.

C) ahead of an advancing cold front.
D) behind an advancing cold front.
Answer: B
10) When an air mass passes from a maritime source region to a warmer continental region,
heating from the warmer land causes
A) frontal lifting.
B) orographic lifting.
C) convectional lifting.
D) adiabatic lifting.
Answer: C
11) Towering cumulonimbus clouds are a common feature in regions where moist unstable air is
heated from below. Such clouds are produced by
A) convectional lifting.
B) orographic lifting.
C) frontal lifting.
D) none of these
Answer: A
12) In orographic lifting, precipitation is associated with the
A) windward slope.
B) the leeward slope.
C) rain shadow.
D) Chinook.
Answer: A

13) If a cool dry day was followed by a warm humid day, you might expect they resulted from
the following consecutive air masses,
A) maritime tropical (mT) followed by continental polar (cP).
B) maritime polar (mP) followed by maritime tropical (mT).
C) continental polar (cP) followed by maritime tropical (mT).
D) continental tropical (cT) followed by continental polar (cP).
Answer: C
14) Heavy snow showers along the western slopes of the Rockies are most likely caused by a
A) continental tropical air mass.
B) maritime tropical air mass.
C) continental polar air mass.
D) maritime polar air mass.
Answer: D
15) Heavy snow showers and low temperatures in Buffalo New York are most likely caused by a
A) continental tropical air mass.
B) continental polar air mass.
C) maritime tropical air mass.
D) maritime polar air mass.
Answer: D
16) Daily afternoon thunderstorms along the Gulf Coast are most likely caused by a
A) continental tropical air mass.
B) continental polar air mass.

C) maritime tropical air mass.
D) maritime polar air mass.
Answer: C
17) Drought conditions and high temperatures over the Great Plains are most likely caused by a
A) continental tropical air mass.
B) continental polar air mass.
C) maritime tropical air mass.
D) maritime polar air mass.
Answer: A
18) Cold damp weather along the eastern coast of the United States is most likely caused by a
A) continental tropical air mass.
B) continental polar air mass.
C) maritime tropical air mass.
D) maritime polar air mass.
Answer: D
19) A drop in pressure is an indication of
A) an approaching cold front.
B) orographic lifting.
C) adiabatic expansion.
D) a stationary front.
Answer: A
20) A rise in pressure is an indication

A) of an approaching cold front.
B) that a cold front has passed.
C) orographic lifting.
D) a stationary front.
Answer: B
21) Rainfall associated with an advancing cold front is generally
A) drizzly.
B) heavy with gusty winds.
C) slow and steady.
D) light to moderate, with steady mild winds.
Answer: B
22) When warm air moves into a cold air mass, the less-dense warmer air rides up over the
colder, denser air. This is very similar to
A) orographic lifting.
B) adiabatic lifting.
C) temperature inversion.
D) what happens during a tornado.
Answer: C
23) In order for clouds to form, air must be lifted. The three principal lifting mechanisms are
A) orographic, condensational, and frontal lifting.
B) orthographic, conversational, and frontal lobotomy.
C) convectional, orographic, and frontal lifting.

D) adiabatic, topographic, and inversional lifting.
Answer: C
24) Which of the following is NOT associated with a cold front?
A) Thunderstorms.
B) Drop in air pressure.
C) Gradually rising warm air.
D) Clear skies behind the front.
Answer: C
25) Behind a warm front, the air is:
A) Cool and wet.
B) Warm and sunny.
C) Warm and wet.
D) Cool and dry.
Answer: B
26) An occluded front can occur when
A) two different air masses are unable to overtake one another.
B) a warm front and a cold front merge.
C) warm air moves into a cold air mass.
D) a cold air mass overtakes a warm air mass.
Answer: B
27) Convectional lifting is caused by
A) circulatory movement deep in Earth's interior.

B) contact of an air mass with warm ground surfaces.
C) the movement of cumulus clouds.
D) humid air rising through the atmosphere.
Answer: B
28) Orographic lifting occurs as
A) two air masses meet head on.
B) air moves over a warm ground surface.
C) an air mass moves into a rain shadow.
D) an air mass is pushed over a mountain range.
Answer: D
29) A rain shadow is associated with
A) the leeward slope of a mountain.
B) orographic lifting.
C) descending dry air.
D) descending dry air on the leeward slope of a mountain.
Answer: D
30) Does Earth's surface significantly influence the flow of air above it?
Answer: Yes! Air moving above Earth's surface picks up the characteristics of the surface. Air
moving over a mountain range may release moisture on the mountains windward side and
generate a rain shadow on its leeward side. Air moving past obstructions can produce gusty
winds.
31) Explain why freezing rain is more commonly associated with warm fronts than with cold
fronts.

Answer: The gradual rise of air means an extended period for the generation of different types of
precipitation. In a warm front, less-dense warm air gradually rides up and over colder, denser air
producing widespread cloudiness and precipitation way before the actual front. In many respects,
a warm front is like a temperature inversion. As the front advances rain or snow develops, and as
winds become brisk, the rain or snow changes to freezing rain. At the front, the air gradually
warms, and the rain or snow turns to drizzle. Behind the front, the air is warm and the clouds
scatter. Change occurs as the air temperature climbs.
32) What are the three main atmospheric lifting mechanisms?
Answer: Convectional lifting due to the unequal heating of Earth's surface. Orographic lifting as
an air mass is pushed up over an obstacle such as a mountain range. Frontal lifting where two
different air masses converge and one is pushed up over the other.
33) Explain how a convection cycle is generated.
Answer: Warm air rises, cool air sinks. Some areas of Earth's surface heat up more readily than
other areas. Air that touches these "hot areas" becomes warmer than the surrounding air. As the
heated air expands it becomes less dense than the surrounding air and is buoyed upward as a
thermal bubble that rises, expands, and cools. This rising of air is accompanied by the sinking of
cooler air aloft. As the cool air sinks to the warm surface, it is heated where it in turn warms and
rises thus repeating the convection cycle.
25.5 Violent Weather
1) In a thunderstorm, the falling rain creates
A) an updraft that generates a storm cell within the cloud.
B) a downdraft, chilling the air and making it denser than the surrounding air.
C) a downdraft, chilling the air and making it less dense than the surrounding air.
D) an updraft, chilling the air and making it denser than the surrounding air.
Answer: B
2) When a funnel cloud touches the ground, it becomes a

A) hurricane.
B) thunderstorm.
C) tornado.
D) cyclone.
Answer: C
3) Hurricanes can be generated
A) in tropical desert areas.
B) from tropical storms with high levels of moisture and thermal energy.
C) as moist thermal winds cross over the equator.
D) by all of these
Answer: B
4) Hurricanes fit into which category below?
A) Cyclones.
B) Anticyclones.
C) Gyres.
D) Cold fronts.
Answer: A
5) Which type of weather is characterized by spiral storms with winds of up to 300 km/hour?
A) Hurricanes.
B) Tornadoes.
C) Tropical depressions.
D) Tropical storms.

Answer: A
6) A hurricane's source of energy is
A) strong winds.
B) evaporation of cool seawater.
C) heat released from condensing water.
D) rapidly sinking air.
Answer: C
7) Lightning occurs as water droplets in a cloud become electrically charged. Energy is
positively charged
A) at the base of the cloud.
B) at the top of the cloud.
C) throughout the cloud.
D) surrounding the cloud.
Answer: B
8) The birth of a thunderstorm occurs when
A) warm, humid air rises in a stable environment.
B) warm, humid air rises in an unstable environment.
C) a cold front encounters a warm front.
D) a maritime polar air mass encounters a maritime tropical air mass.
Answer: B
9) In the Northern Hemisphere, the winds of a tornado travel at speeds of up to 800 km/h in a
A) clockwise direction.

B) counterclockwise direction.
Answer: B
10) Severe thunderstorms are common
A) over the central United States.
B) in Arizona.
C) in the northwestern United States.
D) along the Pacific coast.
Answer: A
11) Although tornadoes occur in many parts of the world, they are very common
A) along the Gulf Coast.
B) in the northeastern part of the United States.
C) in the Central Plains.
D) on the western slopes of the Rockies.
Answer: C
12) Tornadoes are rapidly rotating winds that blow counterclockwise around a small area of
intense
A) high pressure.
B) low pressure.
Answer: B
13) In the Northern Hemisphere, hurricane winds spiral
A) counterclockwise in toward the low pressure zone of the storm's eye.
B) counterclockwise in toward the high pressure zone of the storm's eye.

C) clockwise in toward the low pressure zone of the storm's eye.
D) clockwise in toward the high pressure zone of the storm's eye.
Answer: A
14) The fundamental source of energy released by a tropical hurricane comes from
A) the trade winds.
B) the Sun.
C) warm moist air.
D) the convergence of maritime polar and maritime tropical air masses.
Answer: C
15) The downdraft in a thunderstorm is strengthened as
A) warm moist air sinks in the thunder cell.
B) dry air is drawn into the cloud, raindrops evaporate, and the air chills.
C) cold moist air condenses.
D) precipitation particles grow and fall.
Answer: B
16) In a thundercloud the downdrafts are ________ and the updrafts are ________.
A) warm, cold
B) cold, warm
C) fast, slow
D) slow, fast
Answer: B
17) Hurricanes are more likely to form near

A) warm waters where the air is humid.
B) warm waters where the air is dry.
C) cold bodies of water where the air is humid.
D) cold bodies of water where the air is dry.
Answer: A
18) The energy released by a hurricane comes from
A) cold Atlantic waters.
B) spiraling winds.
C) warm, moist air above warm, tropical oceans.
D) the Sun.
Answer: C
19) Lightning is very common in thunderstorms. Lightning results from
A) an imbalance in energy.
B) a separation of electrical charge within the cloud.
C) air expansion.
D) rising warm updrafts.
Answer: B
20) Lightning occurs as
A) water droplets in a cloud interact with one another, making the cloud electrically charged.
B) electrical energy flows from a cloud to the ground.
C) the surrounding air expands.

D) electric energy flow from cloud to ground as interaction of water droplets electrically charge
the cloud.
Answer: D
21) Briefly describe how thunder and lightning develop.
Answer: Lightning and thunder often accompany thunderstorms. As water droplets in the
thundercloud bump into and rub against one another, the cloud becomes electrically charged–
usually positively charged at the top and negatively charged at the base. As electrical stress
between the oppositely charged regions builds up, the charge becomes great enough that
electrical energy is released and passed to other points of opposite charge, which quite often
means the ground. The electrical energy flow from cloud to ground is lightning. As lightning
heats up the air, the air expands and we hear lightning's noisy companion, thunder.
22) Why are hurricanes more likely to occur on the eastern coast of the United States than on the
western coast?
Answer: Hurricanes need warm water. The warm waters of the Gulf of Mexico and the
Caribbean provide fuel for the development of hurricanes on the eastern coast of the United
States. Although hurricanes do occur on the western coast, the Pacific Ocean is much cooler than
the Gulf and the Caribbean. As such it does not provide the proper fuel for a hurricane.
25.6 The Weather–Number One Topic of Conversation
1) The atmospheric condition at a particular location at a particular moment in time is called
A) weather.
B) climate.
C) average temperature.
D) average precipitation level.
Answer: A
2) All of Earth's weather occurs in the
A) lower levels of the atmosphere.

B) troposphere.
C) tropopause.
D) troposphere and stratosphere.
Answer: B
3) A weather map has many symbols and lines. Isobars are lines that
A) depict wind speed and direction.
B) connect points of equal temperature.
C) connect points of equal pressure.
D) none of the above.
Answer: C
4) Symbols on a weather map are called:
A) Isobars.
B) Data.
C) Weather elements.
D) Weather codes.
Answer: D
5) On a weather map we see an H for Highs and an L for Lows. In a high pressure region we
generally can find
A) stormy weather.
B) clear skies.
C) very cold temperatures.
D) cloud cover.

Answer: B
6) On a weather map, an L depicts an area of low pressure. In this region, if the isobars are
closely spaced around the low, the weather forecast calls for
A) cloudy skies and windy conditions.
B) clear skies with light winds.
C) warm temperatures with light winds.
D) snow.
Answer: A
7) What information is needed in order to forecast today's weather?
Answer: The data needed to forecast today's weather includes all the elements of the air
conditions: temperature, air pressure, humidity, type of clouds, level of precipitation, visibility,
and the direction and speed of the wind.

Test Bank for Conceptual Physical Science
Paul Hewitt, John Suchocki, Leslie Hewitt
9780321752932, 9780134060491

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