Science Chapter 18

water vapor

Which gas is most important for understanding atmospheric processes?
a. oxygen c. water vapor
b. ozone d. carbon dioxide


Rain, snow, sleet, and hail are all examples of


Which of the following can change from one state of matter to another at the temperatures and pressures
experienced at Earth's surface?
a. nitrogen c. water
b. oxygen d. carbon dioxide

0 to 4 percent

Water vapor makes up what fraction of atmospheric gases?


Which term describes the conversion of a solid directly to a gas, without passing through the liquid state?
a. evaporation c. condensation
b. sublimation d. deposition


The process by which water vapor changes directly to a solid is called


The change of state from a gas to a liquid is called


The process of converting a liquid to a gas is known as

latent heat

Which of the following refers to the energy that is stored or released during a change of state of water?
a. caloric heat c. latent heat
b. ultraviolet heat d. evaporation heat


Air that has reached its water-vapor capacity is said to be

it contains more water vapor than old air

What is true about warm, saturated air?

relative humidity

____ 12. The ratio of air's water-vapor content to its capacity to hold water vapor at that same temperature is the

It indicates how near the air is to saturation

What is true about relative humidity?
a. It indicates how near the air is to saturation.
b. It indicates the actual quantity of water vapor in the air.
c. It is the general term used to describe the amount of water vapor in air.

dew point

Which of the following refers to the temperature to which air would have to be cooled to reach saturation?
a. dew point c. adiabatic rate
b. vapor d. relative point

the air has a high relative humidity

When two temperatures read nearly the same on a psychrometer, you can conclude that

increase in relative humidity

If the water-vapor content of air remains constant, lowering air temperature causes a(n)

10 degrees celcius/1000 meters

What is the dry adiabatic rate?


When air expands or contracts, what type of temperature change does it experience?

of the release of latent heat

The wet adiabatic rate of cooling is less than the dry rate because

both a and c

Which of the following occurs when air is compressed?
a. Air temperature rises. c. Air molecules move faster.
b. Air temperature cools. d. both a and c

middle-latitude cyclones

Weather-producing fronts are parts of storm systems called


Which of the following is NOT a process that lifts air?
a. convergence c. divergence
b. orographic lifting d. frontal wedging

frontal wedging

Cool air acts as a barrier over which warmer, less dense air rises, in a process known as


Orographic lifting is associated with

subsidence of an air column

Which of the following will NOT cause air to become unstable?
a. intense solar heating that warms the air from below
b. forceful lifting of air
c. upward movement caused by general convergence
d. subsidence of an air column

afternoon thunderstorms

Which of the following would NOT be associated with stable atmospheric conditions?
a. widespread fog c. temperature inversion
b. afternoon thunderstorms d. buildup of pollutants

it tends to resist rising

What is true about stable air?


Which of the following is NOT produced by condensation?
a. dew c. fog
b. smog d. clouds

all of the above

Which of the following is an example of condensation nuclei?
a. dust c. salt particles
b. smoke d. all of the above


Which cloud type is best described as sheets or layers that cover much or all of the sky?
a. cumulus c. stratus
b. cirrus d. alto


Which cloud type consists of globular cloud masses with a cauliflower structure?
a. cumulus c. stratus
b. cirrus d. alto


Which term is used to describe clouds of middle height?
a. cumulus c. stratus
b. cirrus d. alto

nimbostratus cloud

A low cloud that blankets the sky and often generates precipitation is called a(n)


Which cloud type is confined to the middle height range?


Which term means "rainy cloud"?


Which clouds are often associated with thunder and lightning?

Cool, clear, calm nights

What conditions favor the formation of fog by radiation cooling?

at lower altitudes

Compared to clouds, fogs are

both a and b

Most fogs are the result of which of the following?
a. radiation cooling
b. the movement of air over a cold surface
c. orographic lifting
d. both a and b

The atmospheric subduction process

Which of the following is NOT a process that has been proposed to explain the formation of precipitation?
a. the atmospheric subduction process
b. the collision-coalescence process
c. the Bergeron process
d. none of the above

the bergeron process

Which of the following processes can produce either rain or snow?
a. the Bergeron process
b. the collision-coalescence process
c. both the Bergeron process and the collision-coalescence process

the Bergeron process

In which of the following processes do freezing nuclei play a role?


Which type of precipitation consists of small clear-to-translucent ice particles?


What type of cloud is associated with hail?


Which form of precipitation is likely to occur when a layer of air with temperatures above freezing overlies a
subfreezing layer near the ground?


Water vapor is the source of all condensation and ____________________, which is any form of water that
falls from a cloud.


The process of changing state requires that energy is transferred in the form of __________

ratio, water vapor

Relative humidity is the ____________________ of air's actual water-vapor content compared with the
amount of ____________________ air can hold at that temperature and pressure.


If the water-vapor content of air remains the same, raising air temperature causes a(n)
____________________ in relative humidity.

dry adiabatic

The rate of cooling or heating that applies only to unsaturated air is called the ____________________ rate.


Thermals are ____________________ parcels of warm air


A temperature inversion occurs when air temperature ____________________ with height


If there were no condensation nuclei in the lower atmosphere, a relative humidity much above
____________________ percent would be needed to produce clouds.

form, height

Clouds are classified based on ____________________ and ____________________


_______ is defined as a cloud with its base at or very near the ground

one million

For precipitation to form, cloud droplets must grow in volume by roughly ____________________ times.

temperature profile

___________ describes the way air temperature changes with altitude.

0-4 percent

Water vapor makes up what percentage of gases in the atmosphere?

latent heat of condensation

Stored heat energy released by water molecules during condensation is called what?

amount of water vapor in air

What is humidity?

ratio of airs water vapor to the amount of water vapor the air can actually hold

What is relative humidity?

changing temperature or adding or removing water vapor

How can the relative humidity of a parcel of air be changed?

When air is compressed, it warms, and when it is allowed to expand, it cools

What happens to air temperature when it is compressed or allowed to expand?

orographic lifting, frontal wedging, convergence and localized convective lifting

What four mechanisms cause air to rise?

light to moderate

What type of precipitation, if any, is associated with stable air?

tiny bits of particulate matter that serve as surfaces for water-vapor condensation

What are condensation nuclei?

the method and place of formation

What factors distinguish fog from clouds?

when it is in a liquid state below 0 degrees celcius

When is water said to be supercooled?

the temperature profile in the lower atmosphere

The type of precipitation that reaches Earth's surface depends on what?