WX201 Exam 2

____ appearing in the sky indicates that the mid-level of the troposphere is becoming more unstable.

Altocumulus castellanus

Which condition would be described as the most stable, independent of the season or the location on Earth?

An inversion

Which cloud type below would most likely form in an unstable atmosphere?

Cumulonimbus

Which of the following is not a mechanism primarily responsible for most clouds observed?

Differences in air pressure caused by a rapidly increasing moist adiabatic rate in a thermal.

Rain shadows do not form on the leeward side of mountains.

False

Sinking air sometimes cools adiabatically.

False

Subsidence has no effect on atmospheric stability.

False

The atmosphere is normally most stable in the late afternoon and most unstable in the early morning.

False

The combination of warming the surface and warming the air aloft creates the greatest atmospheric stability

False

The environmental lapse rate is almost always the same as the adiabatic rate.

False

____ is a condition in which the environmental lapse rate is equal to the dry adiabatic rate.

Neutral stability

What transfers heat upwards into the atmosphere?

Thermals

A conditionally unstable atmosphere is stable with respect to unsaturated air and unstable with respect to saturated air.

True

A rising parcel of air expands and cools, whereas a sinking parcel compresses and warms.

True

The atmosphere is normally the most stable in the early morning and the most unstable in the afternoon.

True

The temperature of rising air at a given level inside a cumulus cloud is normally warmer than the air around the cloud.

True

Warm saturated air produces more liquid water than cold saturated air.

True

If the environmental lapse rate is less than the moist adiabatic rate, the atmosphere is ____.

absolutely stable

Altocumulus clouds that show vertical development and produce tower-like extensions are called ____.

altocumulus castellanus

A rising parcel of air that does not exchange heat with its surroundings is an example of ____.

an adiabatic process

An air parcel in an unstable atmosphere has ____ force acting on it.

an upward-directed

Conditional instability occurs whenever the environmental lapse rate is ____ the moist adiabatic rate and the dry adiabatic rate.

between

In a sky filled with scattered cumulus humilis clouds, rising motions are found under the clouds and sinking motions are found ____ the clouds.

between

An inversion represents an extremely stable atmosphere because air that rises into the inversion will eventually become ____ and more dense than/as the surrounding air.

colder

The atmosphere is always absolutely stable when the ____ is less than the moist adiabatic rate.

environmental lapse rate

An example of orographic clouds would be clouds ____.

forming on the windward slope of a mountain

Absolute instability results when the environmental lapse rate is ____ the ____ adiabatic rate.

greater than; dry

In a conditionally unstable atmosphere, the environmental lapse rate will be greater than the moist adiabatic rate and ____ the dry adiabatic rate.

less than

The rate at which the temperature changes inside a descending (or rising) parcel of saturated air is called the ____ rate.

moist adiabatic

Forced lifting along a topographic barrier is called ____.

orographic uplift

A small volume of air is referred to as a ____.

parcel of air

Air that ____ vertical displacements is considered to be stable.

resists

In all seasons, the largest amount of latent heat gets released in a ____ parcel of ____ saturated air.

rising; warm

Most thunderstorms do not extend very far into the stratosphere because the air in the stratosphere is ____.

stable

Inversions that form as air slowly sinks over a large area are called ____ inversions. They sometimes occur at the surface, but more frequently, they are observed aloft and are often associated with large high-pressure areas because of the sinking air motions associated with these systems.

subsidence

The dry adiabatic rate is the rate at which ____.

temperature changes in a rising or descending parcel of unsaturated air

For a layer of altostratus clouds to change into altocumulus it is necessary for ____.

the top part of the cloud deck to cool while the bottom part warms

If rising air cools ____, the relative humidity becomes 100 percent.

to the dew-point temperature

Rising air will eventually cool to its dew-point temperature. At that point, what is its relative humidity?

100

Which environmental lapse rate represents the most unstable atmosphere in a layer of unsaturated air?

11 degrees Celsius per 1,000 m