Deck 6: Stability and Cloud Development

Question 1

Which of the following conditions would be described as the most stable?

A) Environmental lapse rate is 13 C per kilometer.
B) Environmental lapse rate is 3 C per kilometer.
C) isothermal conditions
D) an inversion

Answer 1

an inversion

Question 2

The most latent heat would be released in a ____ parcel of ____ saturated air.

A) rising,warm
B) rising,cold
C) sinking,warm
D) sinking,cold

Answer 2

A

Question 3

A knowledge of air stability is important because

A) it determines the direction of movement of storms.
B) it determines the vertical motion of air.
C) it determines the movement of high pressure areas.
D) it determines seasonal weather patterns.

Answer 3

B

Question 4

At the earth's surface,a rising saturated air parcel would cool most rapidly when its temperature is

A) 10 F.
B) 32 F.
C) 50 F.
D) 68 F.
E) 80 F.

Question 5

Which of the following environmental lapse rates would represent the most unstable atmosphere in a layer of unsaturated air?

A) 3 C per 1,000 m
B) 6 C per 1,000 m
C) 9 C per 1,000 m
D) 11 C per 1,000 m

Question 6

A completely dry air parcel which first rises and cools,and subsequently sinks and warms,is undergoing

A) an irreversible pseudoadiabatic process.
B) a reversible adiabatic process.
C) an irreversible adiabatic process.

Question 7

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 8

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

A) greater,less
B) greater,greater
C) less,greater
D) less,less

Question 9

Which of the following would increase the environmental lapse rate?

A) cold advection at higher altitudes
B) daytime solar heating
C) surface radiational cooling
D) all of the above
E) both cold advection at higher altitudes and daytime solar heating

Question 10

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.

Question 11

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 12

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

A) never
B) sometimes
C) always

Question 13

Vertical mixing of air tends to ____ a large environmental lapse rate.

A) decrease
B) increase

Question 14

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

Question 15

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

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

Question 16

Subsidence inversions are best developed with ____ pressure areas because of the ____ air motions associated with them.

A) high,rising
B) high,sinking
C) low,rising
D) low,sinking

Question 17

Which set of conditions,working together,will make the atmosphere the most stable?

A) Cool the surface and warm the air aloft.
B) Cool the surface and cool the air aloft.
C) Warm the surface and cool the air aloft.
D) Warm the surface and warm the air aloft.

Question 18

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

A) environmental lapse rate.
B) dry adiabatic lapse rate.
C) moist adiabatic lapse rate.
D) latent heat release rate.

Question 19

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.

Question 20

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

A) environmental lapse rate.
B) dry adiabatic rate.
C) moist adiabatic rate.
D) thermocline.

Question 21

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) all of the above

Question 22

Suppose the surface air temperature is 66 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 F per 1,000 feet,the moist adiabatic rate is 3.0 F per 1,000 feet. )

A) 55 F
B) 49 F
C) 46 F
D) 41 F
E) 32 F

Question 23

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

A) air temperature 90 F,dew point temperature 50 F
B) air temperature 90 F,dew point temperature 40 F
C) air temperature 90 F,dew point temperature 60 F
D) air temperature 90 F,dew point temperature 20 F

Question 24

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

Question 25

Which of the following set of surface conditions would produce a convective cumulus cloud with the highest base?

A) air temperature 40 C,dew point 30 C
B) air temperature 25 C,dew point 10 C
C) air temperature 35 C,dew point 10 C
D) air temperature 45 C,dew point 25 C
E) air temperature 25 C,dew point 5 C

Question 26

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

A) unstable,stable
B) unstable,unstable
C) stable,unstable
D) stable,stable

Question 27

____ are found beneath fair-weather cumulus (cumulus humilis)clouds,whereas ____ are found between the clouds.

A) downdrafts,updrafts
B) updrafts,downdrafts
C) downdrafts,only horizontal motions
D) updrafts,only horizontal motions

Question 28

What two sets of conditions,working together,will make the atmosphere the most unstable?

A) Cool the surface and warm the air aloft.
B) Cool the surface and cool the air aloft.
C) Warm the surface and cool the air aloft.
D) Warm the surface and warm the air aloft.

Question 29

Which of the following statements is (are)correct?

A) Convection can occur over the ocean.
B) Air motions are usually downward around a cumulus cloud.
C) The temperature of the rising air at a given level inside a cumulus cloud is normally warmer that the air around the cloud.
D) all of the above

Question 30

Soaring birds in flight,like hawks and eagles,often indicate the presence of

A) irreversible pseudoadiabatic processes.
B) absolute instability.
C) thermals.
D) subsidence inversions.

Question 31

In a rising 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.

Question 32

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

A) stable.
B) unstable.
C) buoyant.
D) dynamic.

Question 33

Which condition below could make a layer of air more unstable?

A) Mix the air in the layer.
B) Lift the entire air layer.
C) Cool the upper part of the layer.
D) all of the above

Question 34

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 35

What would the air temperature inside a conventional jet airliner be,if outside air at an altitude of 10 km,pressure of 250 mb and a temperature of -60 C,is brought inside and compressed to a 1,000 mb pressure? (Hint: you may assume that 1,000 mb pressure is equivalent to 0 m altitude. )

A) -60 C
B) 0 C
C) 40 C
D) 60 C

Question 36

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.

Question 37

The temperature an air parcel would have if it were moved to a pressure of 1,000 mb at the dry adiabatic rate is called the

A) descending temperature.
B) adiabatic temperature.
C) potential temperature.
D) dew point temperature.
E) base temperature.

Question 38

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

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

Question 39

Convective instability associated with severe thunderstorms and tornadoes can be brought on by

A) lifting a stable air layer whose surface is humid and whose top is dry.
B) forcing a layer of moist air to descend a mountain range.
C) heating the upper portion of an unsaturated layer of air.
D) all of the above

Question 40

An example of orographic clouds would be

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

Question 41

What effects might a subsidence inversion have on weather conditions at the ground?

Question 42

Air which resists vertical displacements is considered to be

A) stable.
B) unstable.
C) neutral.

Question 43

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 44

Conditional instability depends on the condition of

A) fog.
B) low pressure.
C) wind.
D) saturation.

Question 45

If a parcel of unsaturated air with a temperature of 30 C rises from the surface to an altitude of 1,000 m,the unsaturated parcel temperature at this altitude would be about

A) 10 C warmer than at the surface.
B) 10 C colder than at the surface.
C) 6 C colder than at the surface.
D) impossible to tell from the data given

Question 46

An air parcel that is warmer than its surroundings will rise.What force accounts for this upward motion?

Question 47

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

A) conditionally unstable.
B) absoutely stable.
C) absolutely unstable.
D) neutrally stable.

Question 48

Sinking air sometimes cools adiabatically.

Question 49

Subsidence ____ stability.

A) increases
B) decreases
C) has little effect on

Question 50

Explain why the surface air on the downwind side of a mountain can be drier than the surface air on the upwind side.What is this effect called? Can you think of a location in the United States where this might actually occur?

Question 51

Would you expect to find a subsidence inversion to be associated with high or low pressure?

Question 52

Does radiational cooling at the ground at night act to increase or decrease atmospheric stability?

Question 53

Based on atmospheric stability considerations,do you think it would be best to burn agricultural debris in the early morning or the afternoon?

Question 54

Explain how the stability of the atmosphere can affect the types of clouds that form.

Question 55

How does daytime heating at the ground during the day affect atmospheric stability?

Question 56

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

A) 25 C.
B) 30 C.
C) 20 C.
D) 15 C.

Question 57

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

A) between,under
B) under,between
C) under,under
D) between,between

Question 58

List and explain the four processes that cause rising air motions in the atmosphere.

Question 59

Explain how lifting an air layer can steepen the environmental lapse rate and make the layer more unstable.

Question 60

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

Question 61

Cumulonimbus clouds indicate unstable atmospheric conditions.What stops the upward growth and causes the top of a cumulonimbus cloud to flatten out into an anvil?

Question 62

Would you expect clear skies to accompany stable,unstable,or neutral stability conditions? Explain your answer.

Question 63

Describe the changes in atmospheric stability throughout a 24 hour period beginning at sunrise on a cloudless summer day over land.

Question 64

What types of clouds might you expect to see form when a cold mass of air moves over warmer water?

Question 65

Suppose you observe lenticular clouds that appear to be motionless.Is the air in the vicinity of the cloud motionless? Explain.