Question 1

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.

Accepted Answer

Ice crystals can grow in a cold cloud even though the supercooled water droplets surrounding them do not because of a process called nucleation. In a cold cloud, the air is saturated with water vapor, but the water droplets remain in a supercooled state, meaning they are below the freezing point but have not yet turned into ice crystals. When an ice crystal is introduced into the supercooled environment, it serves as a nucleation site, meaning it provides a surface for the water molecules to gather and form into an ice crystal. This process is known as heterogeneous nucleation.

Once the ice crystal forms, it can continue to grow as water vapor molecules in the cloud freeze onto its surface, adding to its size. Meanwhile, the supercooled water droplets surrounding the ice crystal remain in a liquid state because they lack a nucleation site to start the ice formation process. This is why ice crystals can grow in a cold cloud even when the surrounding supercooled water droplets do not.

Question 2

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

Accepted Answer

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

Question 3

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

Accepted Answer

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 B

Question 4

In the midlatitudes,most rain results from melted snow that formed from the ice crystal process.

Accepted Answer

A) True 
 B)False

Question 5

Supercooled cloud droplets are:

Accepted Answer

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

Question 6

Large,heavy snowflakes are associated with:

Accepted Answer

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 7

Radar gathers information about precipitation in clouds by measuring the:

Accepted Answer

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 8

The collision-coalescence process is most effective when clouds are made entirely of ice crystals.

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

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

Question 10

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

Accepted Answer

The answer of Explain why it is much more difficult...

Question 11

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

Accepted Answer

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 12

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

Accepted Answer

A) True 
 B)False

Question 13

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.

Accepted Answer

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

Question 14

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

Accepted Answer

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

Question 15

Cloud seeding using silver iodide works well in warm clouds composed entirely of water droplets.

Accepted Answer

A) True 
 B)False

Question 16

During the ice crystal process of rain formation:

Accepted Answer

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 -40o C (-40o F) or below.
D)  the cloud must be a cumuliform cloud.

Question 17

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

Accepted Answer

The answer of What is the main difference between a...

Question 18

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

Accepted Answer

The answer of Thunderstorm cloud bases are generally higher above...

Question 19

After a rainstorm,visibility typically:

Accepted Answer

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

Question 20

Briefly describe the differences in the atmospheric temperature profiles necessary to produce snow,freezing rain,sleet,and hail.

Accepted Answer

The answer of Briefly describe the differences in the atmospheric...

Exam 6: Precipitation Extremes

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.

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

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

In the midlatitudes,most rain results from melted snow that formed from the ice crystal process.

Supercooled cloud droplets are:

Large,heavy snowflakes are associated with:

Radar gathers information about precipitation in clouds by measuring the:

The collision-coalescence process is most effective when clouds are made entirely of ice crystals.

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

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

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

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

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.

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

Cloud seeding using silver iodide works well in warm clouds composed entirely of water droplets.

During the ice crystal process of rain formation:

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

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

After a rainstorm,visibility typically:

Briefly describe the differences in the atmospheric temperature profiles necessary to produce snow,freezing rain,sleet,and hail.