Deck 7: Precipitation

Question 1

Which of the following describes when homogeneous freezing occurs?

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

Answer 1

B

Question 2

Consider a city that receives 12.7 mm of rain in the morning and then 12.7 cm of snow that afternoon. About how much precipitation would Environment Canada report for that day?

A)1.27 cm
B)2.54 cm
C)13.97 cm
D)25.40 cm

Answer 2

B

Question 3

Which of the following 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.

Answer 3

A

Question 4

Which of the following describes the most common snow condition that produces a creaking sound when someone is walking on snow?

A)old snow when the air temperature is above -10°C
B)old snow when the air temperature is near freezing
C)new snow when the air temperature is below -10°C
D)new snow when the air temperature is near freezing

Question 5

Which of the following is the name for a raindrop or partially melted snowflake that freezes into an ice pellet in a deep subfreezing layer of air near the surface?

A)ice pellet
B)freezing rain
C)hail
D)snow

Question 6

Which of the following changes happen as a result of freshly fallen snow?

A)Sound waves are amplified.
B)Sound waves are absorbed.
C)The intensity of visible light is decreased.
D)The intensity of visible light is enhanced.

Question 7

Which of the following conditions are associated with large, heavy snowflakes?

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

Question 8

Which of the following terms refers to a process where a falling ice crystal collides with supercooled water droplets, which stick and freeze?

A)agglomeration
B)nucleation
C)riming
D)deposition

Question 9

Large quantities of which of the following substances are injected into a thunderstorm as the primary method for preventing the growth of large, destructive hailstones?

A)silver iodide
B)hydrophobic nuclei
C)ice crystals
D)dry ice

Question 10

Which of the following statements is accurate when comparing large raindrops to small raindrops?

A)Large raindrops fall faster, and their terminal velocity is higher.
B)Large raindrops fall slower, and their terminal velocity is lower.
C)Large raindrops fall slower, and their terminal velocity is higher.
D)Large raindrops fall faster, and their terminal velocity is lower.

Question 11

Radar measures which of the following to gather information about precipitation in clouds?

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

Question 12

Which of the following defines contact nucleation?

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

Question 13

Which of the following terms refers to the growth of a precipitation particle by the collision of an ice crystal (or snowflake) with a supercooled liquid droplet?

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

Question 14

Which of the following describes supercooled cloud droplets?

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

Question 15

Which of the following statements explains why large cloud droplets fall faster than small cloud droplets?

A)The ratio of the drop's surface area to its weight is smaller.
B)The ratio of the drop's surface area to its weight is larger.
C)Gravity acts more strongly on larger droplets.
D)Gravity acts less strongly on larger droplets.

Question 16

Which of the following occurs during the ice crystal process of rain formation?

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

Question 17

Which of the following conditions are most suitable for natural cloud seeding by ice crystals?

A)stratus clouds above ground fog
B)altocumulus clouds above stratus clouds
C)cirrus clouds above stratus clouds
D)cirrus clouds above altostratus clouds

Question 18

Which of the following is composed of a circular funnel-shaped collector attached to a long measuring tube?

A)standard rain gauge
B)tipping bucket rain gauge
C)calibrated rain gauge
D)weighing-type rain gauge

Question 19

Which of the following is the most accurate when comparing a snow-covered surface to other natural surfaces?

A)the wind speed will be higher over the snow-covered surface
B)the air temperature will be colder over the snow-covered surface
C)precipitation is more likely to fall over the snow-covered surface
D)the air will be more unstable over the snow-covered surface

Question 20

Which of the following gives the name for hail that is deposited in a long, narrow band?

A)squall line
B)hail line
C)ice line
D)hailstreak

Question 21

After a snowstorm, the newspaper reports that a city received 38.1 mm of precipitation. Assuming an average water equivalent ratio for this snowstorm, about how many centimetres of snow did the city receive?

A)3.81 cm
B)7.62 cm
C)22.86
D)39.1 cm

Question 22

Which of the following conditions are necessary for falling snowflakes to survive in air with temperatures much above freezing?

A)unsaturated air and wet-bulb temperature above freezing
B)unsaturated air and wet-bulb temperature at or below freezing
C)saturated air and wet-bulb temperature above freezing
D)saturated air and wet-bulb temperature at or below freezing

Question 23

Which of the following factors makes it possible for condensation on hygroscopic nuclei to occur at relative humidities less than 100 percent?

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

Question 24

Which of the following describes a cloud composed entirely of ice crystals?

A)supersaturated
B)frozen
C)glaciated
D)supercooled

Question 25

On average, the water equivalent of 25.4 cm of snow is about how many centimetres of water?

A)6.35 cm
B)5.08 cm
C)2.54 cm
D)1.27 cm

Question 26

Which of the following indicates the main difference between a cloud drop and a raindrop?

A)shape
B)size
C)colour
D)nuclei

Question 27

Comparing supercooled water and ice, the difference in their saturation vapour pressure reaches a maximum at about -12C. Consequently, the ice crystal process will most effectively produce precipitation at which of the following cloud temperatures?

A)much colder than -1211efbc95_3126_a591_ad5f_1348e684797a_TB1378_00C
B)around -1211efbc95_3126_a591_ad5f_1348e684797a_TB1378_00C
C)much warmer than -1211efbc95_3126_a591_ad5f_1348e684797a_TB1378_00C
D)around 011efbc95_3126_a591_ad5f_1348e684797a_TB1378_00C

Question 28

Glaze is another name for which of the following?

A)freezing rain
B)rime ice
C)ice pellet
D)snow

Question 29

Which of the following terms refers to the merging of liquid cloud droplets by collision?

A)coalescence
B)accretion
C)riming
D)deposition

Question 30

Which of the following is the most common ice crystal shape?

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

Question 31

Which of the following terms refers to rain that falls from a cloud and evaporates before reaching the ground?

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

Question 32

Which of the following is the lightest form of rain?

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

Question 33

Which of the following is the name for a light shower of snow of short duration that falls intermittently from cumuliform clouds?

A)snow flurries
B)a cloud burst
C)a snow squall
D)virga

Question 34

Which of the following two precipitation types require a temperature inversion in the lower troposphere?

A)snow and freezing rain
B)snow and rain
C)rain and ice pellets
D)freezing rain and ice pellets

Question 35

Which of the following is the most likely type of cloud that causes rain to fall on one side of a street and not on the other?

A)stratus cloud
B)altostratus cloud
C)nimbostratus cloud
D)cumulonimbus cloud

Question 36

When the temperature is below freezing from the surface to the 500 hPa pressure level, which precipitation type would be expected?

A)snow
B)rain
C)ice pellets
D)freezing rain

Question 37

Which of the following conditions are probably occurring when large raindrops hit the ground?

A)thick cloud overhead and weak updrafts
B)thick cloud overhead and strong updrafts
C)thin cloud overhead and weak updrafts
D)thin cloud overhead and strong updrafts

Question 38

In Ontario, most precipitation that falls to the surface as rain originally formed as which precipitation type?

A)rain
B)freezing rain
C)ice pellets
D)snow

Question 39

Which of the following cloud types produces precipitation by the collision-coalescence process only?

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

Question 40

At which of the following air temperatures is aircraft icing most severe?

A)1°C
B)-5°C
C)-12°C
D)-18°C

Question 41

Which of the following processes typically occurs before fallstreaks reach the ground?

A)evaporation
B)deposition
C)sublimation
D)condensation

Question 42

Which of the following types of clouds most often form fallstreaks?

A)cirrus
B)stratus
C)nimbostratus
D)cumulonimbus

Question 43

Which of the following is the most important factor in the production of raindrops?

A)the liquid-water content of the cloud
B)the updrafts within the cloud
C)the cloud thickness
D)the range of droplet sizes within the cloud

Question 44

Which of the following clouds is most likely to produce drizzle?

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

Question 45

Which of the following statements best describes the curvature effect?

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

Question 46

Which of the following is the name for an amount of precipitation that is less than 0.2 mm?

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

Question 47

Consider the winter scenario in which a large section of the Prairies has had no electricity due to downed power lines. Which of the following forms of precipitation most likely produced this situation?

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

Question 48

Which of the following typically happens to visibility after a rainstorm?

A)It deteriorates.
B)It improves at first, but then deteriorates.
C)It is unaffected.
D)It improves.

Question 49

Which of the following is the name for snowflakes and ice crystals falling from high cirriform clouds?

A)snow squalls
B)graupel
C)fallstreaks
D)snow flurries

Question 50

Which of the following best describes the solute effect?

A)Cloud droplets evaporate and ice crystals grow in a cold cloud.
B)Pollutants are removed from the atmosphere by cloud droplets.
C)Water droplets are kept from freezing at temperatures below 0°C.
D)Dissolution of hygroscopic nuclei occurs as does condensation at relative humidities less than 100 percent.

Question 51

Which of the following types of precipitation most likely forms when the surface air temperature is slightly below freezing and the air temperature increases with an increasing distance above the ground?

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

Question 52

Which of the following is the expected temperature at which a cloud becomes completely glaciated?

A)0°C
B)-5°C
C)-18°C
D)-40°C

Question 53

Which of the following forms of precipitation has the greatest diameter?

A)hailstone
B)snow grain
C)ice pellet
D)graupel

Question 54

Which of the following are the two main substances used in cloud seeding?

A)silver iodide and lead iodide
B)lead iodide and dry ice
C)ice crystals and flood powder
D)silver iodide and dry ice

Question 55

In which of the following conditions does cloud seeding work using silver iodide only?

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

Question 56

Which of the following substances may be ice nuclei?

A)polycarbonates
B)certain clay minerals
C)metamorphic crystals
D)bacteria in living plant leaf material

Question 57

Which of the following statements describes the size of a typical raindrop compared to a typical cloud droplet?

A)A typical raindrop is 1000 times larger.
B)A typical raindrop is 100 times larger.
C)A typical raindrop is 100 times smaller.
D)A typical raindrop is 1000 times smaller.

Question 58

Do the largest forms of precipitation particles occur during the warmest or the coldest time of year? Explain.

Question 59

Which of the following might be mistaken for hail?

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

Question 60

Satellites measure rainfall from space using which of the following instruments?

A)ceilometer
B)calibrated rain gauge
C)tipping-bucket rain gauge
D)radar

Question 61

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

Question 62

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

Question 63

Why might a radar display indicate that precipitation is falling when in fact none is reaching the surface?

Question 64

Does the heaviest snowfall occur on an unusually cold night or a night when the temperature is just a little below freezing? Explain.

Question 65

About how large can raindrops get? Why can't they get any larger? What shape does a large raindrop have? What forces determine this shape?

Question 66

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

Question 67

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

Question 68

Explain why the curvature effect acts to inhibit the growth of small droplets.

Question 69

How do the height and thickness of clouds influence the probability of precipitation?

Question 70

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

Question 71

Explain why snowflakes differ in appearance depending on the moisture content in the air.

Question 72

In the ice-crystal process of precipitation formation, why does water vapour diffuse from liquid droplets toward ice crystals?

Question 73

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 74

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

Question 75

Why are raindrops less than 2 mm nearly spherical in shape but larger raindrops have slightly flatter bottoms?

Question 76

Explain why the middle parts of clouds have so few ice crystals despite temperatures there that are well below freezing.

Question 77

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

Question 78

How are snowflakes able to fall in air temperatures that are above freezing?