133 terms


Relative humidity depends on the water vapor present in the air and the
forces the air to rise.
A convergence of winds near the surface is associated with cloud production because it
is released to the nearby air.
When water vapor condenses, the heat involved
warming temperatures.
Sinking or subsiding air cannot form clouds due to the
increase, increase
If the air temperature remains constant, evaporating water into the air will ________ the dew point and ________ the relative humidity.
increases with an increase in temperature.
The capacity of the air to hold water vapor
evaporation, condensation.
The two changes of state that are the most important part of the water cycle for the atmosphere would be
As the temperature of air is reduced to its dew point, which of these is most likely to occur?
cooling by expansion of air.
The most important process of cloud formation in the atmosphere is:
subsidence of an air column
Which of the following will not cause air to become more unstable?
afternoon thundershowers
Which of the following would not be associated with stable atmospheric conditions?
clear skys are associated with subsidence or sinking motion Adiabatic temperature changes refer to parcels of air that rise
or sink.. If the mixing ratio remains unchanged and the More water is evaporated from the oceans than is returned to the oceans by precipitation.temperature drops, the relative humidity will increase.
The formation of hoar frost is an example of deposition. An area that is very cold in winter will probably also have a
relatively dry winter. The average annual precipitation for the
Earth is equal to the annual amount of evaporated water. The capacity of air to hold water vapor is temperature When air sinks, it is compressed and warmed.dependent.
localized convective lifting
Thermals are created by the lifting mechanism known as ________.
sublimate or deposit gram of water
If you know the amount of heat it takes to melt gram of water and turn it to vapor, you also know the amount of heat it takes to do this: ________.
Saturation usually results from the air rising, which results in cooling to the dew point as the air expands.
What is the usual cause of the air becoming saturated?
haze or air pollution and fog
List two atmospheric phenomena in air near the surface that are likely when the air is very stable.
Water is evaporating from the wick of the wet bulb. This evaporation removes heat from the thermometer and cools it.
Why does the wet bulb thermometer of a psychrometer read less than the dry bulb?
During a wet adiabatic process, water vapor condenses. This releases latent heat which partially reduces the cooling process.
Why is the wet adiabatic rate of cooling less that the dry adiabatic rate?
the temperature lapse rate
To make a decision about the stability of the air, what is the most important information that you need to know?
runoff, infiltration, evaporation
Once precipitation has fallen on land, it may take one of three paths. List these three possible routes.
clear calm nights.
Dew is most likely to form on
warm surface air temperatures.
All of the following are necessary ingredients for cloud formation EXCEPT:
can allow cloud droplets to form even if the relative humidity is less than percent.
Hygroscopic nuclei:
more than percent.
A cloud that forms liquid droplets has a relative humidity of percent with respect to the liquid droplets. If ice crystals form in this cloud, they will experience the cloud environment as having a relative humidity of
It is raining on only one side of your street. The cloud above you is
Luke Howard
Who first created the cloud classification system on which our modern system is based?
Arica, Chile
Where is the dryest place on Earth?
You are flying in an airplane at , feet above sea level. You see lightning outside your plane window. The cloud that is close by is
Which of these is a mid-level cloud?
to the lee of mountains
Where are lenticular clouds most likely to form?
high cloud...stratus
Which association is not correct?
lenticularassociated with rainbows
Which association is not correct?
low cloud...stratus
Which association is correct?
Increase the daily temperature range.
How are jet contrails thought to influence the surface temperatures of cities near major airports?
large numbers of supercooled droplets.
The necessary conditions for hail formation include strong upward vertical motion and
rising and expanding.
The most common way for air to be cooled in order that a cloud may form is by
electrical charges on the droplets.
The formation of raindrops by collision and coalescence of smaller cloud droplets is strongly influenced by
Cloud formation releases latent heat to the air.
Why do clouds represent a source of heat for the atmosphere?
Clouds which have extensive vertical dimensions are
grow much more rapidly.
The important difference between liquid droplets and ice crystals in a supercooled cloud is that ice crystals
condensation nuclei.
The cloud droplets in a cloud are formed by water vapor molecules and
moist air moving over a cold surface.
The conditions that persist along the West Coast of the U.S. that are conducive to fog formation are
air being cooled as it rises.
Clouds and precipitation form in the air primarily due to
The process by which a cloud droplet first forms is
The water content or volume of a raindrop is approximately ________ times that of a typical cloud droplet.
Which of these clouds is least likely to produce precipitation that reaches the ground?
still liquid at temperatures below degrees C.
Supercooled water is water which is
Condensation is too slow.
What is the basic reason why condensation is not very important in causing a cloud droplet to grow to raindrop size?
Very little water vapor is present.
Why are high altitude clouds always so thin?
upper air is warm and surface air is cold.
Freezing rain (ice storm or sleet occurs when
obvious vertical dimension.
A cumulus cloud is recognized mainly by its
form or appearance.
Clouds are classified and named according to their altitude and
cooling by expansion of the air.
The most important process for cloud formation in the atmosphere is
collision and coalescence.
The raindrops that fall to Earth from a warm cloud contain about one million times the water in a typical cloud droplet. This growth from cloud droplet to raindrop occurs mainly because of
the Bergeron process.
Most of the precipitation that falls in the middle latitudes is formed by:
about equal to the dew point.
Dew point is the temperature at which water vapor in the air begins to condense. The temperature inside a cloud would therefore be
the air being cooled.
Clouds, dew and frost all form because air has become saturated. This condition of saturation is usually caused by
The cloud form that is best described as sheets or layers that cover much or all of the sky is termed:
cumulonimbus clouds.
Hail is most commonly associated with:
spontaneous freezing of large water droplets.
The growth of a hailstone usually involves everything EXCEPT:
When warm moist air moves over a cold surface, ________ fog may result.
radiation fog
Which type of fog occurs during nights when skies are clear and relative humidity is high?
steam fog.
The type of fog produced when cold air moves over a warm, moist surface is called:
This cloud sometimes produces mare's tails.
The ________ cloud may have an "anvil head."
Thunder and lightning are associated with the ________ cloud.
A(n ________ is a layer of dark gray clouds that produces precipitation.
The ________ cloud is confined to the middle height range.
A HALO around the Sun or the Moon indicates the cloud ________ is present.
condensation nuclei.
Salt, dust particles, silver iodide, and combustion by-products are all examples of:
Of the following cloud types, which is most likely to produce the most rain?
Contrails formed by aircrafts most closely mimic which type of cloud?
high relative humidity and clear nighttime skies
A radiation fog requires which of the following in order to form?
the saturation vapor pressure is lower near ice crystals than it is near supercooled droplets.
The Bergeron process causes cloud droplets to grow because:
wind causes snow to vary in depth across the surface.
Snowfall depths can be difficult to measure because:
cloud seeding.
The process of releasing silver iodide into the atmosphere to stimulate rainfall is called:
silver iodide crystals act as freezing nuclei and enhance the Bergeron process.
The process of cloud seeding is based on the theory that:
to prevent or lessen damage to crops and property.
The primary motivation for hail suppression experiments is:
Successful dispersal of fog by seeding is limited to supercooled fog. Accurate measurement of precipitation is limited by the effects of the wind. Frost prevention by air mixing requires that a temperature inversion be present in the air layer near the ground.Water condensation can occur even if the air is not saturated.
Contrails can last long periods of time if they form in air that is near saturation.
Radiation fog evaporates from the bottom up. Most rainfall begins as snow or other forms of frozen water. Tornadoes are
only associated with cumulonimbus clouds. Nimbostratus clouds can produce long, steady periods of precipitation.
The type of fog that frequently exists along the California coast is an advection fog. Cloud seeding can be used to disperse fog.
Freezing rain falls as a liquid and freezes once its on the ground. Cumulus clouds can develop as a consequence of local convection. Stratus clouds can form in air that is very stable.
Frost tends to form when the surface dew point temperature is below freezing. At - degrees C, clouds contain both ice crystals and supercooled water droplets.
Which cloud type is most likely to produce a brief yet intense period of precipitation?
Frost is an example of ________.
Steam fogs and frontal fogs are both types of ________ fogs.
The most effective cloud condensation nuclei are water absorbent, i.e., ________.
Radar can measure the intensity of precipitation and the height where it forms in the cloud; radar does not detect cloud droplets.
What measurement does radar provide concerning clouds and precipitation?
Snow depth and the liquid water equivalent of the snow.
When snow is the form of precipitation, two separate measurements are required; list them.
Drops growing larger than this will break apart from the effects of air friction. The result forms or more smaller drops.
Why are raindrops that reach the ground limited to a maximum size of about mm in diameter?
They are so light that their fall speed is very slow. This would result in their evaporation before reaching the ground.
Why do the liquid droplets that form a cloud (cloud droplets not fall to the ground as a fine drizzle?
Strong vertical motion and a large amount of supercooled water drops.
List the two requirements that a cumulonimbus cloud must meet if hail is to form.
cooled to its dew-point temperature at the lifting condensation level.
When will an ascending parcel of air begin to condense into a cloud?
The pressure gradient force is directed from higher to lower pressure
pressure gradient force.
The force that generates wind is:
remove the effects of elevation.
Meteorologists convert all atmospheric pressure data to the equivalent sea-level air pressure in order to:
The addition of water vapor will cause the density of air to:
air moving out of an area.
Divergence in the atmosphere is best defined as:
produces strong winds.
A steep pressure gradient:
lines connecting points of equal air pressure
What do isobars represent on a map?
speed and latitude
Which of these factors influence the magnitude of the Coriolis force?
are faster than surface winds.
Upper air winds:
relatively dry conditions.
High air pressure zones are usually associated with:
If "fair" weather is approaching, the pressure tendency would probably be:
converging winds and ascending air result over the land.
When air moves from the ocean onto land:
Which of the following has the smallest impact on winds?
proportional to the force acting on it and inversely proportional to its mass.
Newton's second law of motion states that an object's acceleration is
its rotation.
The Coriolis effect occurs because of this characteristic of the Earth:
outward and counterclockwise.
In the southern hemisphere, anticylonic winds flow
inward and counterclockwise.
In the northern hemisphere, cyclonic winds flow
speed and direction.
The effect of friction on the wind alters its
at high altitudes.
The geostrophic wind concept is most like the real atmospheric winds
As seen by an observer on Earth, the Coriolis effect is an illusion; no deflection can actually be measured.
When geostrophic conditions exist in the
atmosphere, the net force on the moving air is
Coriolis force.
Instead of the air flowing straight out of a high pressure system, it spirals out in a clockwise direction. The cause of the clockwise spiraling motion is
pressure gradient force.
The primary force which causes ALL winds is
cover long distances.
The Coriolis effect is important only for motions that
changing the direction of the wind.
The Coriolis effect influences the wind by
Low wind speedsstrongest deflection
With respect to the Coriolis force, which association is NOT correct?
parallel to the isobars.
The geostrophic wind describes a situation where the air moves
very much slower.
Weather reports of wind express only the horizontal motion of the air. The vertical component of the air motion is usually
uneven heating of the Earth's surface.
Horizontal variations in air pressure cause a force which makes the wind blow. These pressure variations are caused by
Friction reduces the speed so Coriolis is weakened.
Why do surface winds cross the isobars at an angle toward lower pressure (instead of blowing parallel to the isobars)?
friction is present only close to the ground.
The wind speed normally increases with height in the layer of air next to the ground. This illustrates the fact that
balloon ascent from sea level to miles
Which of the following would involve the greatest change in atmospheric pressure?
pressure gradient and Coriolis.
Neglecting friction, the speed and direction of the horizontal wind are determined by
temperature contrasts between different locations.
Circulations in the Earth's atmosphere are fundamentally caused by
its pressure gradient.
The overall strength of a circulation system is determined by
air would move directly from high to low pressure.
If the Earth were not rotating,
weight of the air above.
The best explanation for the cause of atmospheric pressure is
change in pressure along a horizontal surface.
The term pressure gradient refers to