Deck 7: Precipitation

Question 1

Condensation onto hygroscopic nuclei is possible at relative humidities less than 100 percent due to the

A) curvature effect.
B) electrical charge on these nuclei.
C) solute effect.
D) crystalline structure of these nuclei.

Answer 1

C

Question 2

Ice nuclei may be

A) ice crystals.
B) certain clay minerals.
C) bacteria in decaying plant leaf material.
D) all of the above

Answer 2

D

Question 3

Contact nucleation is

A) the freezing of supercooled droplets by contact with a nucleus.
B) the sticking together of ice crystals to make a snowflake.
C) the joining of many nuclei to form an ice nucleus.
D) the freezing of supercooled droplets when they come into contact with a supercooled surface.

Answer 3

A

Question 4

What are the two main substances used in cloud seeding?

A) lead iodide,dry ice
B) silver iodide,lead iodide
C) ice crystals,flood powder
D) dry ice,sea salt
E) silver iodide,dry ice

Question 5

Supercooled cloud droplets are

A) ice crystals surrounded by air warmer than 0 C (32 F).
B) liquid droplets that are cooler than the air around them.
C) liquid droplets observed at temperatures below 0 C (32 F).
D) water droplets that have had all their latent heat removed.

Question 6

Which cloud would most likely produce drizzle?

A) stratus
B) cumulus
C) cumulus congestus
D) cirrostratus
E) cumulonimbus

Question 7

Homogeneous nucleation occurs when

A) water vapor condenses onto hygroscopic nuclei.
B) water vapor condenses onto hydrophobic nuclei.
C) water vapor condenses without nuclei.
D) all the condensation nuclei are exactly the same.

Question 8

Which below best describes the solute effect?

A) keeps water droplets from freezing at temperatures below 32 F
B) removal of pollutants from the atmosphere by cloud droplets
C) water droplets dissolve hygroscopic nuclei and condensation can occur at relative humidities less than 100 percent
D) evaporation of cloud droplets and grow of ice crystals in a cold cloud

Question 9

Which cloud type below will only produce precipitation by the collision-coalescence process?

A) a thick,cold nimbostratus cloud
B) a thick,warm cumulus cloud
C) a thick,cold cumulus cloud
D) a thick,supercooled cumulonimbus cloud with abundant nuclei
E) a supercooled cumulus congestus cloud

Question 10

If you observe large raindrops hitting the ground,you could probably say that the cloud overhead was ____ and had ____ updrafts.

A) thick,weak
B) thick,strong
C) thin,weak
D) thin,strong

Question 11

Which of the following statements is NOT correct?

A) Generally,the smaller the pure water droplet,the lower the temperature at which it will freeze.
B) Ice nuclei are more plentiful in the atmosphere than condensation nuclei.
C) Much of the rain falling in middle northern latitudes begins as snow.
D) Ice crystals may grow in a cold cloud even though supercooled droplets do not.

Question 12

During the ice crystal process of rain formation,

A) only ice crystals need be present in a cloud.
B) ice crystals grow larger at the expense of the surrounding liquid cloud droplets.
C) the temperature in the cloud must be -40C (-40 F)or below.
D) the cloud must be a cumuliform cloud.

Question 13

The growth of a precipitation particle by the collision of an ice crystal (or snowflake)with a supercooled liquid droplet is called

A) accretion.
B) spontaneous nucleation.
C) condensation.
D) deposition.

Question 14

Which of the following is NOT an important factor in the production of rain by the collision-coalescence process?

A) the updrafts in the cloud
B) relative size of the droplets
C) the number of ice crystals in the cloud
D) cloud thickness
E) the electric charge of the droplets

Question 15

Which statement below best describes the curvature effect?

A) Large cloud droplets fall faster than small droplets.
B) Small droplets evaporate more quickly than large droplets.
C) Small droplets collide and coalesce more easily than larger droplets.
D) It explains the six-sided shape of ice crystals.

Question 16

At the same sub-freezing temperature,the saturation vapor pressure just above a liquid water surface is ____ the saturation vapor pressure above an ice surface.

A) greater than
B) the same as
C) less than

Question 17

Cloud seeding using silver iodide only works in

A) cold clouds composed entirely of ice crystals.
B) warm clouds composed entirely of water droplets.
C) cold clouds composed of ice crystals and supercooled droplets.
D) cumuliform clouds.

Question 18

If rain falls on one side of a street and not on the other side,the rain most likely fell from a

A) nimbostratus cloud.
B) stratus cloud.
C) cumulonimbus cloud.
D) altostratus cloud.
E) altocumulus cloud.

Question 19

The temperature at which you would expect a cloud to become completely glaciated is

A) 0 C (32 F).
B) -5 C (23 F).
C) -18 C (0 F).
D) -40 C (-40 F).

Question 20

Large raindrops fall ____ than smaller raindrops,and have a ____ terminal velocity than small raindrops.

A) faster,lesser
B) faster,greater
C) slower,lesser
D) slower,greater

Question 21

A true blizzard is characterized by

A) low temperatures.
B) strong winds.
C) reduced visibility.
D) blowing snow.
E) all of these

Question 22

An amount of precipitation measured to be less than one hundredth of an inch (0.25 mm)is called

A) a trace.
B) drizzle.
C) light rain.
D) mist.

Question 23

The largest snowflakes would probably be observed in ____ air whose temperature is ____ freezing.

A) moist,near
B) dry,near
C) moist,well below
D) dry,well below

Question 24

After a snowstorm,the newspaper reports that Buffalo,New York,received 1.50 inches of precipitation.If we assume an average water equivalent ratio for this snowstorm,then Buffalo received about ____ inches of snow.

A) 3
B) 1.5
C) 10
D) 9
E) 15

Question 25

Precipitation with the greatest size (diameter)is

A) the snow pellet.
B) the snow grain.
C) a hailstone.
D) sleet.
E) a rain drop.

Question 26

The primary method used in preventing the growth of large,destructive hailstones is to inject a thunderstorm with large quantities of

A) silver iodide.
B) ice crystals.
C) dry ice.
D) hydrophobic nuclei.
E) hailstone embryos.

Question 27

Fall streaks usually ____ before reaching the ground.

A) evaporate
B) condense
C) sublimate
D) deposit

Question 28

Which is NOT a correct association?

A) snow grains - hail
B) ground blizzard - drifting and blowing snow
C) snow squall - intense snow shower
D) sleet - ice pellet
E) freezing rain - glaze

Question 29

Large,heavy snowflakes are associated with

A) dry air and temperatures well below freezing.
B) moist air and temperatures well below freezing.
C) dry air and temperatures near freezing.
D) moist air and temperatures near freezing.

Question 30

On average,the water equivalent of 10 inches of snow is about ____ inches of water.

A) 0.5
B) 1
C) 2
D) 2.5
E) 5

Question 31

In the winter you read in the newspaper that a large section of the Midwest is without power due to downed power lines.Which form of precipitation would most likely produce this situation?

A) snow
B) hail
C) freezing rain
D) sleet
E) rain

Question 32

Which below best describes why a fluffy covering of snow is able to protect sensitive plants and their root systems from damaging low temperatures?

A) Snow is a good insulator.
B) Melting snow releases latent heat.
C) Snow is a good emitter of infrared energy.
D) Snow is a good reflector of sunlight.

Question 33

Fall streaks most often form with

A) nimbostratus clouds.
B) cumulonimbus clouds.
C) stratus clouds.
D) altostratus clouds.
E) cirrus clouds.

Question 34

After a rainstorm,visibility typically

A) deteriorates.
B) is unaffected.
C) improves.

Question 35

In order for falling snowflakes to survive in air with temperatures much above freezing,the air must be ____ and the wet bulb temperature must be ____.

A) unsaturated,at or below freezing
B) unsaturated,above freezing
C) saturated,at or below freezing
D) saturated,above freezing

Question 36

The most common ice crystal shape is

A) graupel.
B) dendrite.
C) rime.
D) virga.

Question 37

Which of the following might be mistaken for hail?

A) virga
B) graupel
C) dendrite
D) supercooled droplet

Question 38

If a city were to receive 1/2 inch of rain in the morning and then 5 inches of snow that afternoon,about how much precipitation would the weather service report for that day?

A) 5 1/2 inches
B) 1/2 inch
C) 1 inch
D) 10 inches

Question 39

Rain which falls from a cloud but evaporates before reaching the ground is referred to as

A) sleet.
B) virga.
C) graupel.
D) dry rain.

Question 40

Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?

A) freezing rain
B) hail
C) rain
D) snow
E) drizzle

Question 41

In a typical advancing winter storm,which of the following sequences of precipitation types is most likely to occur?

A) rain,freezing rain,snow,sleet
B) rain,sleet,freezing rain,snow
C) freezing rain,rain,sleet,snow
D) rain,freezing rain,sleet,snow

Question 42

A typical raindrop is about ____ than a typical cloud droplet.

A) one thousand times smaller
B) one thousand times larger
C) one hundred times smaller
D) one hundred times larger

Question 43

Would you expect the largest forms of precipitation particles to occur during the warmest or the coldest time of year? Explain.

Question 44

The difference in saturation vapor pressure between supercooled water and ice reaches a maximum at about -12 C.This means that the ice crystal process will be most effective in producing precipitation when cloud temperatures are

A) much colder than -12 C.
B) around -12 C.
C) much warmer than -12 C.

Question 45

Would you expect the heaviest snowfall to occur on an unusually cold night or a night when the temperature was just a little below freezing?

Question 46

About how large can raindrops get? Why can't they get any larger?

Question 47

Satellites measure rainfall from space using which instrument?

A) radar
B) tipping-bucket rain gauge
C) ceiliometer
D) all of the above
E) none of the above

Question 48

The main difference between a cloud drop and a raindrop is its

A) color.
B) size.
C) shape.
D) none of the above

Question 49

Briefly describe the differences between snow,freezing rain,sleet and hail.

Question 50

Thunderstorm cloud bases are generally higher above the ground in Arizona than in Florida.Why?

Question 51

The first raindrops to reach the ground at the beginning of a rain shower are often very large.Explain why this is so.

Question 52

Freshly fallen snow ____ sound waves.

A) amplifies
B) absorbs
C) none of the above

Question 53

Large cloud droplets fall faster than small cloud droplets because

A) the ratio of the drop's surface area to its weight is larger.
B) the ratio of the drop's surface area to its weight is smaller.
C) gravity acts more strongly on larger droplets.
D) the speed of the falling drop increases until the air resistance equals the pull of gravity.

Question 54

Is silver iodide used as a cloud seeding agent in warm or cold clouds? Why?

Question 55

Radar gathers information about precipitation in clouds by measuring the

A) energy emitted by the precipitation particles.
B) absorption characteristics of falling precipitation.
C) amount of energy reflected back to a transmitter.
D) amount of sunlight scattered off the precipitation.
E) amount of solar energy passing through the cloud.

Question 56

The lightest form of rain is

A) shower.
B) cloudburst.
C) virga.
D) drizzle.

Question 57

What is the main difference between a raindrop and a cloud droplet?

Question 58

Explain why it is possible for an ice crystal to grow in a cold cloud even though the supercooled water droplets surrounding the ice crystal do not.

Question 59

What shape does a large raindrop have? What forces determine this shape?

Question 60

Saturation vapor pressure ____ as temperature increases.
a.
increases
b.
decreases
c.
can't

Question 61

When precipitation is falling in the form of sleet,what conclusions can you make regarding the vertical profile of temperature between the ground and the cloud?

Question 62

Design an automated device for measuring snowfall.How might it work?

Question 63

How is precipitation measured using Doppler radar?

Question 64

Given that precipitation can be accurately measured at surface weather stations,explain why it is desirable to measure rainfall from space.

Question 65

Explain why it is much more difficult to measure snowfall amount than rainfall amount.