Deck 7: Precipitation Processes

Question 1

The terminal velocity of an object depends primarily upon:

A)its composition.
B)its shape.
C)its size.
D)the temperature.

Answer 1

C

Question 2

The collision efficiency:

A)is approximately one regardless of drop size.
B)is affected by the compression of air just below the collector drop.
C)is governed primarily by the temperature of the air.
D)is highest for droplets of equal or nearly equal size.

Answer 2

B

Question 3

During coalescence,the percentage of colliding droplets that join together is called the:

A)droplet collection coefficient.
B)coalescence efficiency.
C)rain potential efficiency.
D)coalescence condensation collection factor.
E)none of the above

Answer 3

B

Question 4

Ice crystal growth rates are enhanced by which of the following?

A)deposition of water vapor to ice alone
B)riming
C)aggregation
D)all of the above

Question 5

The process by which supercooled water droplets freeze onto falling ice crystals is called:

A)riming.
B)aggregation.
C)cold-cloud condensation.
D)Bergeron bonding.

Question 6

Drag between the droplet and surrounding air depends on:

A)the rate of fall.
B)the size of the droplet.
C)both A and B
D)none of the above

Question 7

Cool clouds:

A)contain no water droplets above 0 degrees Celsius.
B)contain substantial numbers of ice crystals at all elevations within the clouds.
C)have regions with above-freezing temperatures.
D)typically form precipitation through the collision-coalescence process.

Question 8

The smallest terminal velocities are for:

A)condensation nuclei.
B)cloud droplets.
C)raindrops.
D)none of the above

Question 9

Terminal velocity is achieved when:

A)you enter the freeway from the on-ramp.
B)Nolan Ryan's fastball impacts the catcher's mitt.
C)gravity is equalized by spinning.
D)there is a balance between the falling body and the drag of atmospheric molecules.

Question 10

Collision-coalescence is the predominant cause of precipitation in this region:

A)above the Arctic Circle.
B)subpolar latitudes.
C)mid-latitudes.
D)the Tropics.

Question 11

In the Bergeron-Findeisen process,the cloud is:

A)raining.
B)snowing.
C)sleeting.
D)entirely above freezing.
E)Part of the cloud is above freezing, and part of the cloud is below freezing.

Question 12

In the collision-coalescence process,the entire cloud is:

A)raining.
B)snowing.
C)below freezing.
D)above freezing.

Question 13

Formation of ice crystals can occur with saturation at temperatures between:

A)0 and 5 degrees C.
B)0 and -5 degrees C.
C)-4 and -40 degrees C.
D)-40 and -60 degrees C.

Question 14

A collector drop will have the highest collision efficiency with this size drop:

A)drops that are much larger.
B)drops that are about the same size.
C)drops that are somewhat smaller.
D)drops that are very much smaller.

Question 15

Cloud droplets fall slowly because they:

A)are small.
B)carry an electric charge.
C)easily get caught in downdrafts.
D)have not adhered to condensation nuclei.

Question 16

The collision-coalescence process:

A)is most common at high latitudes.
B)is most frequent in cold clouds.
C)is dependent upon the different downward velocities of different-sized droplets.
D)explains the formation of snow better than it explains the formation of rain.

Question 17

Cloud droplet growth by condensation is very rapid for:

A)large cloud droplets.
B)supercooled water droplets.
C)ice crystals.
D)small cloud droplets.
E)none of the above

Question 18

Raindrops fall because:

A)they are large compared to atmospheric molecules.
B)they are small compared to atmospheric molecules.
C)they become large enough that gravity can pull them out of the sky.
D)they roll down isentropic surfaces and can't be stopped.

Question 19

The acceleration of gravity is opposed by the atmosphere in the form of:

A)drag.
B)viscosity.
C)thermal inversions.
D)winds.

Question 20

The Bergeron process:

A)is most common in the Tropics.
B)is dependent on the growth of ice crystals.
C)can take place in cool clouds, but not cold clouds.
D)is not dependent on changes in vapor pressure.

Question 21

Rainshowers:

A)typically come from cumuliform clouds.
B)are, by definition, periods of rain that last for at least one hour.
C)have only one size of raindrop.
D)usually have their origin in orographic lifting.

Question 22

The average precipitation for the entire world is:

A)25 inches.
B)39 inches.
C)45 inches.
D)53 inches.

Question 23

Which of the following cloud constituents would have the highest terminal velocity?

A)condensation nuclei
B)raindrops
C)hailstones
D)ice crystals

Question 24

Newton's Second Law:

A)holds that the net force on an object is the product of the object's mass and its acceleration.
B)does not take into account the effects of drag on a falling object.
C)explains why a falling object will accelerate indefinitely.
D)is not adequate for the study of falling droplets; Einstein's relativity equations must be applied.

Question 25

In comparison to liquid water,the density of the ice in hail is:

A)50% of water.
B)70% of water.
C)90% of water.
D)no difference

Question 26

Rain that falls in an almost random,stop-and-start manner is called:

A)virga.
B)warm frontal precipitation.
C)showers.
D)squalls.

Question 27

In the winter of 1976-77,areas of northern New York state received:

A)10 feet.
B)17 feet.
C)25 feet.
D)33 feet.

Question 28

The greatest recorded seasonal snowfall ever recorded in the United States was recorded at Mt.Baker Lodge in Washington,with an amount of:

A)33 feet.
B)67 feet.
C)90 feet.
D)110 feet.

Question 29

Aggregation:

A)is the first step of the Bergeron process.
B)works best when the cloud temperature is -10 degrees Celsius or colder.
C)is facilitated by a thin coating of water on ice crystals.
D)is another term for riming.

Question 30

Which of the following geographic areas are associated with the collision-coalescence process?

A)polar areas
B)high latitude
C)mid-latitudes
D)tropics

Question 31

In the western part of North America,snowfall distribution is primarily dependent upon:

A)latitude.
B)the presence of major north-south mountain ranges.
C)proximity to Mexico.
D)the location of large lakes.

Question 32

Raindrops are initially what kind of shape?

A)teardrop
B)oblong
C)spherical
D)cylindrical

Question 33

The most important principle underlying the Bergeron process is this:

A)for a given temperature, the saturation vapor pressure of ice is less than that for supercooled water.
B)large drops fall faster than smaller drops.
C)aggregation takes place more rapidly than accretion.
D)the bottom part of the cloud where the process is taking place must be warmer than 0 degrees Celsius.

Question 34

Average annual snowfall in North America:

A)in general decreases with increasing latitude.
B)is very high in parts of British Columbia.
C)peaks along the southern shores of Hudson Bay.
D)is highest in upstate New York.

Question 35

The largest form of precipitation is:

A)rain.
B)snow.
C)drizzle.
D)graupel.
E)hail.

Question 36

Of the following steps in the Bergeron process,which should be second?

A)formation of rain drops
B)the falling of ice crystals through the cloud
C)deposition of water vapor on ice
D)net evaporation from supercooled water droplets

Question 37

Which of the following is a widely held misconception about snowfall and temperature?

A)It's too cold to snow.
B)It's too cold to snow a lot.
C)Snow only falls at the freezing point.
D)none of the above

Question 38

The shape of a raindrop:

A)remains constant throughout the journey from cloud to ground.
B)is initially that of a tear.
C)flattens out on the bottom as it falls.
D)is not affected by drag.

Question 39

In middle latitudes,rain:

A)usually begins as snow.
B)is formed by the collision-coalescence process.
C)is less common than in high latitudes.
D)is incapable of turning to sleet.

Question 40

Lake-effect snowfall:

A)is most common in late winter.
B)requires that the lake be relatively warm.
C)extends for up to 100 miles south of the lake.
D)requires the presence of stable air.

Question 41

Freezing rain:

A)requires a layer of cold air near the surface.
B)is not associated with temperature inversions.
C)leaves the bottom of clouds as supercooled droplets.
D)is commonly associated with thunderstorms.

Question 42

Snow results from all of the following processes,except:

A)riming.
B)deposition.
C)coalescence.
D)aggregation.

Question 43

Raindrops fall to the ground when:

A)they are at least five times the size of a cloud droplet.
B)they reach a large enough terminal velocity for both their size and the distance between them and the ground.
C)they are able to catch a fast-moving downdraft.
D)the coalescence rate exceeds that of the collision rate.

Question 44

Graupel:

A)has sharp edges.
B)can be as large as hail.
C)can provide the nuclei for hail.
D)does not contain air bubbles.

Question 45

Wet growth of a hailstone occurs in an environment

A)with weak upper-level winds.
B)where the temperature is well below freezing.
C)where repeated trips are made through a cloud.
D)where the temperature is near freezing.

Question 46

Globally,annual precipitation amounts are highest in the:

A)mid-latitudes.
B)tropical rain forests of South America and Africa.
C)east coast of Asia.
D)northern Europe.

Question 47

Dry growth of a hailstone occurs in an environment

A)where repeated trips are made through a cloud.
B)where the temperature is well below freezing.
C)with weak upper-level winds.
D)where the temperature is near freezing.

Question 48

Precipitation in the eastern two-thirds of North America:

A)increases with increasing latitude.
B)is dominated by lake-effect snowfalls.
C)is influenced by the Gulf of Mexico.
D)does not show any longitudinal differences.

Question 49

Which of the following are associated with orographic uplift?

A)Central Valley
B)Sierra Nevada
C)Willamette Valley
D)Puget Sound

Question 50

Sleet:

A)requires the presence of a warmer above-freezing inversion layer.
B)freezes immediately upon touching the surface.
C)is usually associated with a cold front.
D)is more dangerous than freezing rain.

Question 51

Hail:

A)requires very strong downdrafts.
B)most frequently occurs in sizes greater than two centimeters in diameter.
C)can provide the nucleus for graupel formation.
D)usually forms in cumuliform clouds.

Question 52

Lake effect precipitation is caused by:

A)wind blowing over a frozen lake surface.
B)wind blowing over an unfrozen lake surface.
C)a land breeze.
D)orographic effects only.
E)none of the above

Question 53

With reference to the Great Lakes,which of the following mechanisms are favorable for precipitation in that area?

A)initial mechanism for uplift
B)unstable air
C)sufficient moisture
D)all of the above

Question 54

When ice crystals grow primarily through riming:

A)the result will be powder snow for skiers.
B)the formation must be taking place in very cold clouds.
C)the resulting snowflakes will be so small that they will gently float to the ground.
D)the result will be a dense and wet snow.

Question 55

Snowflakes:

A)rarely exceed a tenth of a millimeter in size.
B)form different crystal patterns in different parts of the country.
C)will grow very different types of crystals even at the exact same conditions.
D)can be a combination of several different forms.

Question 56

Hail forms:

A)during the coldest time of year because it is the largest form of precipitation.
B)as a result of added uplift over mountains.
C)during the warmest time of the year because this is when the thunderstorm updrafts are strongest.
D)only in the summer and early fall.

Question 57

During the formation of snow,the atmospheric temperature profile is:

A)almost entirely below freezing.
B)below freezing in the upper part of the atmosphere.
C)below freezing in the lower part of the atmosphere.
D)above freezing in the middle part of the atmosphere.
E)none of the above

Question 58

What happens to a raindrop if it gets too large?

A)evaporates
B)stays suspended in the cloud
C)breaks up into smaller drops
D)turns into a hailstone

Question 59

The growth of ice crystals in the Bergeron-Findeisen process occurs because:

A)the relative humidity is higher in a cold cloud than in a warm cloud.
B)of the difference between saturation vapor pressure between ice and water.
C)liquid water is attracted to ice because of an electrical charge differential.
D)updrafts are extremely strong during the Bergeron-Findeisen process.

Question 60

Given that the diameter of the average raindrop is 100 times that of the average cloud droplet,the volume of the average raindrop is about this many times greater than that of the average cloud droplet:

A)100 times.
B)1000 times.
C)10000 times.
D)1000000 times.

Question 61

The primary ethical issue associated with the practice of cloud seeding is

A)the concern that areas downwind of a seeded cloud will be deprived of precipitation
B)the concern that resources devoted to cloud seeding activities would be better used in other activities
C)the concern that cloud seeding should only be attempted by professional meteorologists
D)the concern that cloud seeding introduces toxic chemicals into the environment

Question 62

Lake-effect snow is most common near this lake:

A)Lake Tahoe.
B)Great Salt Lake.
C)Lake Erie.
D)Lake Champlain.

Question 63

Cloud seeding is most likely to be successful in areas with:

A)flat terrain.
B)small, rolling hills.
C)a continual uplift of air.
D)clouds that naturally contain some dry ice.

Question 64

Precipitation measured by weather radar

A)is based on the inability of falling droplets, ice crystals and hailstones to scatter radiation
B)is based on the emission of radiation by falling droplets, ice crystals and hailstones
C)is based on the absorption of radiation by falling droplets, ice crystals and hailstones
D)is based on the scattering of radiation by falling droplets, ice crystals and hailstones

Question 65

Which of the following weather modification efforts has been the most successful?

A)hail suppression in New York
B)hurricane suppression along the Gulf Coast
C)snowfall enhancement in Colorado
D)fog dissipation in Montana

Question 66

The objective of cloud seeding is

A)to cause more droplets in a cloud to become supercooled
B)to convert some of the supercooled droplets in a cool cloud to ice and cause precipitation by the Bergeron process
C)to convert some of the supercooled droplets in a cool cloud to ice and cause precipitation by the collision/coalescence process
D)to enhance the evaporation of supercooled cloud droplets

Question 67

Cloud seeding:

A)has been of substantial benefit to farmers on the Great Plains.
B)uses dry ice to increase the temperature of very cold clouds.
C)uses silver iodide to promote homogeneous nucleation.
D)has been able to increase rainfall in the Sierra Nevada under certain conditions.

Question 68

The agent ________ is used in cloud seeding in the hope that it will act as an ice nucleus.

Question 69

In the United States,hail is most common in which of the following regions?

A)West Coast
B)East Coast
C)Great Plains
D)Gulf Coast

Question 70

Describe the two main methods of cloud seeding and evaluate how effective cloud seeding efforts have been.

Question 71

How does weather radar estimate precipitation amounts and distances?

Question 72

Average annual precipitation is highest:

A)in the coastal mountains of British Columbia.
B)along the Atlantic coast of the southern United States.
C)in California's Sierra Nevada.
D)in the area immediately south of the Great Lakes.

Question 73

Rainfall is measured directly by

A)a standard rain gauge
B)a tipping bucket rain gauge
C)a weighing bucket rain gauge
D)weather radar

Question 74

The fact that rain gauges provide point measurements

A)make them exactly as useful as precipitation measurements by radar
B)makes it difficult to determine the horizontal extent of precipitation from the measurements.
C)makes them particularly useful in determining the horizontal extent of precipitation from the measurements
D)reduces their measurement errors

Question 75

The effectiveness of cloud seeding is

A)widely debated
B)generally accepted
C)highest in areas that typically receive extremely high rainfall
D)highest in remote oceanic areas

Question 76

Snow measurement:

A)is best done with a rain gauge.
B)usually involves estimating the water content of snow.
C)can only be measured by human beings.
D)uses the same instruments as does rain measurement.

Question 77

One difficulty in evaluating the effectiveness of cloud seeding is

A)it is impossible to determine the presence of updrafts in the region of a precipitating cloud
B)it is impossible to determine the temperature in the region of a precipitating cloud
C)it is impossible to determine the stability in the region of a precipitating cloud
D)it is impossible to determine whether a seeded cloud would have produced precipitation even if it were not seeded

Question 78

Schaefer and Langmuir discovered that dry ice could be used as a cloud seeding agent during which decade?

A)1940s
B)1920s
C)1960s
D)1970s

Question 79

Which of the following is not an application of cloud seeding?

A)fog removal at airports
B)reduction of hail intensity
C)reducing the likelihood of rainfall
D)inducing precipitation from clouds

Question 80

The typical snow to rain water equivalent ratio is

A)10:1.
B)1:10.
C)100:1.
D)1:65.
E)3:4.