Deck 6: Stability and Cloud Development

Question 1

​When there is an extremely small amount of moisture in the air, the moist adiabatic rate of cooling would be almost equal to the dry adiabatic rate.

Answer 1

True

Question 2

Usually when a cumulonimbus cloud begins to dissipate, the bottom half of the cloud dissipates first.​

Answer 2

True

Question 3

​Sinking air sometimes cools adiabatically.

Answer 3

False

Question 4

Billow clouds form along the top of a cloud layer when changes in wind speed and direction reach a critical value, and an inversion caps the cloud-forming layers.

Question 5

​The temperature of rising air at a given level inside a cumulus cloud is normally warmer than the air around the cloud.

Question 6

A layer of altostratus can change into one of altocumulus, if the top of the original cloud deck cools while the bottom warms.​

Question 7

​Convective instability associated with severe thunderstorms and tornadoes can be brought on by lifting a stable air layer whose surface is humid and whose top is dry.

Question 8

​Environmental lapse rate and dry adiabatic rate are different expressions for the same phenomenon.

Question 9

​Subsidence has no effect on atmospheric stability.

Question 10

Subsidence inversions are just as common on Earth's surface as they are aloft.​

Question 11

Cumulus clouds are a common phenomenon over cool water surfaces.​

Question 12

The safest place to build an airport in a mountainous region is along a deep valley.​

Question 13

It is possible for a layer of air to be convectively unstable and absolutely stable at the same time.​

Question 14

​The environmental lapse rate is almost always the same as the adiabatic rate.

Question 15

Clouds help regulate Earth's energy balance by reflecting and scattering solar radiation and by absorbing Earth's infrared energy.​

Question 16

If an air parcel is given a small push upward and it falls back to its original position, the atmosphere is said to be​

A) ​stable.
B) ​unstable.
C) ​isothermal.
D) ​neutral.
E) ​adiabatic.

Question 17

Cirrostratus, altostratus, nimbostratus, and stratus clouds are associated with stable atmospheric conditions.​

Question 18

The environmental lapse rate decreases due to cold advection at higher altitudes and daytime solar heating.

Question 19

The up and down motions in layered clouds produce globular elements that give the clouds lumpy appearances.​

Question 20

​The combination of warming the surface and warming the air aloft creates the greatest atmospheric stability.

Question 21

An inversion represents an extremely stable atmosphere because air that rises into the inversion will eventually become ____ and ____ dense than the surrounding air.​

A) ​warmer; less
B) ​warmer; more
C) ​colder; less
D) ​colder; more
E) ​warmer; similarly

Question 22

The rate at which the actual air temperature changes with increasing height above the surface is referred to as the ____ rate.​

A) ​dry adiabatic
B) ​environmental lapse
C) ​moist adiabatic
D) ​thermoclinic
E) ​absolute stability

Question 23

The dry adiabatic rate is the rate at which​

A) ​an air parcel rises.
B) ​temperature changes in a rising or descending parcel of unsaturated air.
C) ​volume changes when a parcel expands or is compressed.
D) ​latent heat energy is released in a rising air parcel.
E) ​temperature changes in a rising or descending parcel of saturated air.

Question 24

If rising air cools to its dew-point temperature, the relative humidity becomes ____.​

A) ​20%
B) ​40%
C) ​60%
D) ​80%
E) ​100%

Question 25

The difference between "moist" and "dry" adiabatic rates is due to the fact that​

A) ​saturated air is always unstable.
B) ​an unsaturated air parcel expands more rapidly than a saturated air parcel.
C) ​moist air weighs less than dry air.
D) ​latent heat is released by a rising parcel of saturated air.
E) ​moist air weighs more than dry air.

Question 26

In a conditionally unstable atmosphere, the environmental lapse rate will be ____ the moist adiabatic rate and ____ the dry adiabatic rate.​

A) ​greater than; less than
B) ​greater than; greater than
C) ​less than; greater than
D) ​less than; less than
E) ​the same as; the same as

Question 27

Which cloud type below would most likely form in an unstable atmosphere?​

A) ​cumulonimbus
B) ​stratus
C) ​cirrostratus
D) ​nimbostratus
E) ​cumulus humilis

Question 28

​Which of the following sets of conditions would produce a cumulus cloud with the lowest base?

A) ​air temperature 90 $\degree$ F, dew point temperature 50 $\degree$ F
B) ​air temperature 90 $\degree$ F, dew point temperature 40 $\degree$ F
C) ​air temperature 90 $\degree$ F, dew point temperature 60 $\degree$ F
D) ​air temperature 90 $\degree$ F, dew point temperature 20 $\degree$ F
E) ​air temperature 90 $\degree$ F, dew point temperature 10 $\degree$ F

Question 29

In a rising unsaturated thermal, the dew-point temperature​

A) ​increases at a slower rate than the parcel temperature.
B) ​decreases at the same rate as the parcel temperature.
C) ​decreases at a slower rate than the parcel temperature.
D) ​increases at a faster rate than the parcel temperature.
E) ​always remains the same.

Question 30

Just above cumulus clouds, you would expect to find​

A) ​a stable layer.
B) ​an unstable layer.
C) ​a conditionally unstable layer.
D) ​unusually strong horizontal winds.
E) ​convective instability.

Question 31

Which condition would be described as the most stable?​

A) ​environmental lapse rate is 13 $\degree$ C per kilometer
B) ​environmental lapse rate is 3 $\degree$ C per kilometer
C) ​isothermal conditions
D) ​an inversion
E) ​superadiabatic conditions

Question 32

The rate at which the temperature changes inside a rising (or descending) parcel of saturated air is called the ____ rate.​

A) ​environmental lapse
B) ​dry adiabatic
C) ​moist adiabatic
D) ​latent heat release
E) ​specific heat release

Question 33

​The dry adiabatic rate is ____ greater than the moist adiabatic rate.

A) ​never
B) ​sometimes
C) ​always
D) ​most of the time
E) ​half the time

Question 34

A knowledge of air stability is important because it determines​

A) ​the direction of movement of storms.
B) ​the vertical motion of air.
C) ​the movement of high pressure areas.
D) ​seasonal weather patterns.
E) ​the movement of low pressure systems.

Question 35

A rising parcel of air that does not exchange heat with its surroundings is an example of​

A) ​isothermal ascent.
B) ​an adiabatic process.
C) ​forced lifting.
D) ​advection.
E) ​convection.

Question 36

At Earth's surface, a rising saturated air parcel cools at the​

A) ​moist adiabatic rate.
B) ​dry adiabatic rate.
C) ​condensation rate.
D) ​saturation rate.
E) ​development rate.

Question 37

​If an air parcel is given a small push upward and it continues to move upward on its own accord, the atmosphere is said to be dynamic.

A) ​stable.
B) ​unstable.
C) ​buoyant.
D) ​dynamic.
E) ​supersaturated.

Question 38

Most thunderstorms do not extend very far into the stratosphere because the air in the stratosphere is​

A) ​unstable.
B) ​stable.
C) ​too cold.
D) ​too thin.
E) ​too dry.

Question 39

Which environmental lapse rate represents the most unstable atmosphere in a layer of unsaturated air?​

A) ​1 $\degree$ C per 1,000 m
B) ​3 $\degree$ C per 1,000 m
C) ​6 $\degree$ C per 1,000 m
D) ​9 $\degree$ C per 1,000 m
E) ​11 $\degree$ C per 1,000 m

Question 40

The largest amount of latent heat gets released in a ____ parcel of ____ saturated air.​

A) ​rising; warm
B) ​rising; cold
C) ​sinking; warm
D) ​sinking; cold
E) ​stagnant; medium-temperature

Question 41

​Absolute instability results when the environmental lapse rate is ____ the ____ adiabatic rate.

A) ​greater than; moist
B) less than; moist
C) the same as; dry
D) ​greater than; dry
E) ​less than; dry

Question 42

​If you were to take a trip during the summer from Ohio to Nevada, you would most likely observe that afternoon cumulus clouds ____ as you travel west.

A) ​have higher cloud bases
B) ​are larger
C) ​form earlier in the day
D) ​disappear
E) ​form later in the day

Question 43

Air which resists vertical displacements is considered to be​

A) ​stable.
B) ​unstable.
C) ​neutral.
D) ​supersaturated.
E) ​entrained.

Question 44

Which condition below is necessary for a layer of altostratus clouds to change into altocumulus?​

A) ​The top part of the cloud deck cools while the bottom part warms.
B) ​Temperature increases with increasing altitude in the layer.
C) ​The cloud layer becomes more stable.
D) ​The cloud layer becomes clear.
E) ​The nuclei types within the cloud have to change.

Question 45

​Conditional instability occurs whenever the environmental lapse rate is ____ the moist adiabatic rate and the dry adiabatic rate.

A) ​higher than
B) ​less than
C) ​between
D) ​the same as
E) ​double

Question 46

​On rare occasions when the environmental lapse rate exceeds about ____ (the autoconvective lapse rate), convection becomes spontaneous, resulting in the automatic overturning of the air.

A) ​3.4 degrees Celsius per 10 m
B) ​3.4 degrees Celsius per 1,000 m
C) ​34 degrees Celsius per 100 m
D) ​34 degrees Celsius per 10,000 m
E) ​3.4 degrees Celsius per 100 m

Question 47

Which process below will change a moist layer of stable air into a deck of low stratocumulus clouds?​

A) ​mixing
B) ​lifting
C) ​cooling the surface
D) ​heat the top of the layer
E) ​subsidence

Question 48

​The elevation where clouds form is called ____ level.

A) ​condensation
B) ​saturation
C) ​precipitation
D) ​cloud formation
E) ​adiabatic

Question 49

If the environmental lapse rate is less than the moist adiabatic rate, the atmosphere is​

A) ​conditionally unstable.
B) ​absolutely stable.
C) ​absolutely unstable.
D) ​neutrally stable.
E) ​superadiabatic.

Question 50

The best time of day for a farmer to burn agricultural debris for least polluted conditions is​

A) ​first thing in the morning
B) ​at noon.
C) ​at sunset.
D) ​during the night.
E) during the afternoon.

Question 51

​An air parcel in an unstable atmosphere has ____ force acting on it.

A) ​no
B) ​a sideways-directed
C) ​a downward-directed
D) ​a diagonally-directed
E) ​an upward-directed

Question 52

​In a sky filled with scattered cumulus humilis clouds, rising motions are found ____ the clouds and sinking motions are found ____ the clouds.

A) ​between; above
B) ​under; between
C) ​under; under
D) ​between; between
E) ​above; under

Question 53

An example of orographic clouds would be clouds​

A) ​forming over a warm ocean current.
B) ​forming on the windward slope of a mountain.
C) ​forming behind a jet airplane.
D) ​formed by surface heating.
E) ​forming on the leeward side of a mountain.

Question 54

​Suppose the surface air temperature is 66 $\degree$ F. If the base of a cumulus congestus cloud directly above you is 2,000 feet, what would be the approximate temperature at an altitude of 5,000 feet above you inside the cloud? (Hint: the dry adiabatic rate is 5.5 $\degree$ F per 1,000 feet, the moist adiabatic rate is 3.0 $\degree$ F per 1,000 feet.)

A) ​55 $\degree$ F
B) ​49 $\degree$ F
C) ​46 $\degree$ F
D) ​41 $\degree$ F
E) ​32 $\degree$ F

Question 55

What transfers heat upward into the atmosphere?​

A) ​cloud streets
B) ​billows
C) ​thermals
D) ​subsidence inversions
E) ​pockets of saturated air

Question 56

An example of orographic clouds would be​

A) ​cumulus clouds produced by surface heating.
B) ​rotor clouds.
C) ​lee-wave clouds.
D) ​clouds that form on the upwind slope of a mountain.
E) ​pileus clouds.

Question 57

Conditional instability depends on the condition of​

A) ​fog.
B) ​low pressure.
C) ​wind.
D) ​saturation.
E) ​subsidence.

Question 58

​When cloud elements become arranged in rows they are called cloud

A) ​roads.
B) ​trails.
C) ​billows.
D) ​rows.
E) ​streets.

Question 59

If the environmental lapse rate is 5 $\degree$ C per 1,000 m and the temperature at Earth's surface is 25 $\degree$ C, then the air temperature at 2,000 m above the ground is​

A) ​25 $\degree$ C.
B) ​30 $\degree$ C.
C) ​20 $\degree$ C.
D) ​15 $\degree$ C.
E) ​10 $\degree$ C.

Question 60

​Forced lifting along a topographic barrier is called ____.

A) ​orographic rising
B) ​orographic uplift
C) ​topographical uplift
D) ​topographical uprise
E) ​orographic uprise

Question 61

​Dry adiabatic cooling and warming rates are approximately ____ of change in elevation.

A) ​4 degrees Celsius for every 1000 m
B) ​6 degrees Celsius for every 1000 m
C) ​8 degrees Celsius for every 1000 m
D) ​10 degrees Celsius for every 1000 m
E) ​12 degrees Celsius for every 1000 m

Question 62

​The stability of the atmosphere above the condensation level plays a major role in determining the vertical growth of a cumulus cloud. When a deep conditionally unstable layer exists above the cloud base, ____ are likely to grow.

A) ​cumulus humilis
B) ​billow clouds
C) ​cumulus congestus
D) ​cumulonimbus
E) ​lenticular clouds

Question 63

Rain shadows form on the ____________________ side of mountains.

Question 64

In an air parcel the average speed of the molecules is directly related to the air ____________________, and the molecules colliding against the parcel walls determine the air ____________________ inside.​

Question 65

​An afternoon sky full of cumulus humilis clouds with little vertical growth indicates ____ weather.

A) stormy
B) fair
C) ​cold
D) snowy
E) rainy

Question 66

When the environmental lapse rate exceeds the dry adiabatic rate, the lapse rate is called ____________________.​

Question 67

​At Earth's surface, a parcel of air has ____ the air surrounding it.

A) ​the same temperature, but lower pressure than
B) ​a lower temperature, but higher pressure than
C) ​a higher temperature, but lower pressure
D) ​a higher temperature, but the same pressure as
E) ​the same temperature and pressure as

Question 68

​Inversions that form as air slowly sinks over a large area are called ____ inversions.

A) ​surface
B) ​surficial
C) ​ground-cover
D) ​ground
E) ​subsidence

Question 69

​A conditionally unstable atmosphere is ____________________ with respect to unsaturated air and ____________________ with respect to saturated air.

Question 70

​Altocumulus clouds that show vertical development and produce tower-like extensions are called

A) ​cumulus.
B) ​cumulonimbus.
C) ​cumulus humilis.
D) ​altocumulus castellanus.
E) ​cirrocumulus castellanus.

Question 71

​Convective instability is associated with the development of

A) ​foggy weather.
B) ​dew frost.
C) hazy conditions.
D) ​prolonged fair weather.
E) ​severe storms, such as thunderstorms and tornadoes.

Question 72

​Vertical mixing of air tends to ____________________ the environmental lapse rate.

Question 73

​A(n) ____________________ process is a process in which an air parcel expands and cools, or compresses and warms, with no interchange of heat with its surroundings.

Question 74

When rising air cools to its dew-point temperature, its relative humidity typically is ____ percent.​

A) ​60
B) ​70
C) ​80
D) ​90
E) 100​

Question 75

When air is stable and close to saturation stratocumulus clouds can be produced by a process called ____________________.​

Question 76

Unlike the dry adiabatic rate, the moist adiabatic rate is not constant, but varies greatly with ____________________ and, hence, with moisture content.​

Question 77

​Altocumulus castellanus appearing in the sky indicates that the mid-level of the troposphere is becoming

A) ​more unstable.
B) ​less unstable.
C) ​conditionally stable.
D) ​more stable.
E) ​more conditionally stable.

Question 78

​Inversions that form as air slowly sinks over a large area are called ____________________ inversions.

Question 79

If the atmosphere is conditionally unstable, the condition necessary to bring on instability is called ____________________.​

Question 80

Lenticular clouds form on the ____________________ side of mountains.​