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Dew is most likely to form on

Clear calm nights

All of the following is necessary for cloud formation EXCEPT

Warm surface air temperatures

Hygroscopic Nuclei

small particles on which water vapor can condense or sublime.

A cloud that forms liquid droplets has a relative humidity of 100 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

100 percent

Its raining on only one side of your street. The cloud above you is


High clouds are those that form at altitudes of at least:

above 20,000 feet

You observe a cloud at an altitude of 3000 m. This cloud name would have the prefix


Where are lenticular clouds most likely form?

on the lee side of mountains; they form whenever the airflow undulates sharpley in the veritcal.

The most common way for ait to be cooled in order that a cloud may form is by

Rising and Expanding

The important difference between liquid droplets and ice crystals in a supercooled cloud is that ice crystals

grow much more rapidly

The conditions that persist along the West Coast of the U.S. that are conducive to fog formation are

Moist air moving over a cold surface

The process by which a cloud droplet first forms is


What is the basic reason why condensation is not very important in cuasing a cloud droplet to grow to a raindrop size?

Condensation is too slow

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

Collision and Coalescence

Clouds, dew and frost all form because air has become saturated. This condition of saturation is usually caused by

Air being Cooled

When warm moist air moves over a cold surface,_____ fog may result.

Advection fog

Which type of fog occurs during nights when skies are clear and relative humidity is high?

Radiation Fog

The type of fog produced when cold air moves over a warm, moist surface is called

Steam fog

Cloud involving Thunder and Lightning


A halo around the Sun or the Moon indicates this cloud


Salt, dust particles, silver iodide, and combustion by-productions are all examples of

Condensation Nuclei

Advection fogs form best when there is no wind


A steep pressure gradient produces

Strong winds

Hydrostatic Equilibrium is best defined as

an upward directed vertical pressure gradient, which is usually balanced by gravity.

If the Earth were not rotating:

Air would move directly from high to low pressure

Meteorologists convert all atmospheric pressure data to the equivalent sea-level air pressure in order to

remove the effects of elevation

The Coriolis effect influences the wind by

Changing the direction of the wind

The Coriolis effect occurs because of this characteristic of the Earth:

its rotation

The Coriolis effect is important only for motions that

Cover long distances

The addition of water vapor will cause the density of air to


The best explanation for the cause of atmospheric pressure is

Gravity. Atmospheric pressure is the weight of a column of air. Of course, the temperatuer of that air changes its density and therefore its weight.

The effect of friction on the wind alters its

Speed and Direction

The force that generates wind is

Pressure gradient force

Geostrophic wind concept is most like the real atmospheric winds

at high altitudes

The pressure gradient force is directed from higher to lower pressure

this force is called the pressure gradient force

The primary force which causes ALL winds is

pressure gradient force

The term pressure gradient refers to

the spacing of the isobars which indicates the amount of pressure change occurring over a given distance

What do isobars represent on a map?

areas on a map of atmospheric pressure

When density remains constant and the temperature is lowered, the pressure of a confined gas


Why do surface winds cross the isobars at an angle toward lower pressure?

because of Frictional Force

According to Hadley, the most important factor causing circulation patterns in the atmosphere was

Temperature contrasts between the equator and pole

Concerning rainfall patterns, areas of persistent high pressure tend to cause

desert regions. This is because high pressure systems have sinking mechanisms, which prevent the formation of clouds and precipitation.

Dust Devils

type of microscale circulation, a well-developed vortex

El Nino events are characterized by

unusually warm ocean temperatures in the Equatorial Pacific

Most of the U.S. is situated in which zone of prevailing winds?


The term "Hadley Cell" applies to

0 deg to 30 deg latitude

Zonal refers to the east-west direction while meridional refers to the north-south direction


a CT air mass is

Continental Tropical Air; source region for cT air is the desert southwest. Skies are usually clear. This allows daytime heating during the day and radiational cooling at night.

An air mass from the Gulf of Mexico is called:

-mT; Maritime Tropical

An air mass is a body of air with

Characteristics of temperature, moisture, and pressure that are approximately uniform horizontally.

An mP air mass is

Maritime Polar; The source region for mP air is over cold ocean currents or high latitude ocean waters. Not much moisture content as cT air.

Characters of an air mass source region include

the location where the different types of air masses formed. Generally very large. Example: Ocean

Compared to continental air masses with the same air temperature, maritime air masses:

Continental tropical air masses form over tropical or subtropical water, resulting in their warm temperature. Maritime forms over Polar regions

This air mass may produce an occasional "nor'easter" in the winter

Maritime Polar

The two most important properties that should be relatively homogeneous at the same altitude in an air mass are

Temperature and amount of moisture at any given altitude.

Which of the following occurs only in summer in North America?

Maritime Polar

Which region of origin for mT air masses has the most impact on North American weather?

Western U.S.

A wind shift in a counterclockwise direction, as from east to north is

Backing wind shift

A wind shift in a clockwise direction, as from south to west is

Veering wind shift

As a warm front approaches, which progression of clouds are you most likely to see

cirrus, altostratus, stratus, nimbostratus

Tornadoes are generally associated with which type of front

A cold front moving into moist air

A trough aloft is generally associated with

Lows at the surface

A warm front is said to exist when

advancing warm air overrides retreating cold air

The lifting of air and the resulting formation of clouds and rain is more gradual for a

warm front

The more violent nature of weather produced by a cold front can be attributed to which two factors

Steep slope, fast forward motion of front

Why is the number and intensity of wave cyclones greatest during the late fall, winter, and spring months

Temperatures are below freezing

Which of these best describes the reason most high pressure systems bring clear skies?

sinking air aloft

Which of these is common to both cold and warm fronts?

lifting of warm air over cold

Compared to other types of fronts, the weather associated with a cold front usually

is more violent but of shorter duration

About how many thunderstorms take place on Earth every day?


Which of the following U.S. states experience the most thunderstorms each year?


Which of the following should have the steepest pressure gradient?


Which of the following is likely during the mature stage of a thunderstorm?


Which type of lightning is least likely?

Cloud to cloud lightning

Thunderstorms form when

Warm, humid air rises in an unstable environment

Some of the most dangerous weather is produced by a type of thunderstorm called a


Strong tornado, maximum winds approach

300 mph

Relatively narrow, elongated bands of thunderstorms that develop in the warm sector of a middle-latitude cyclone, usually in advance of a cold front

Squall lines

Fewest weather related deaths in the U.S.


What causes the dissipating stage of a thunderstorm?

spreading downdraft cuts off air flow

Why do most tornadoes in the central U.S. occur during the spring months?

Air-mass contrasts are greatest

Conventional radar measures

rainfall intensity

Why is very humid air near the surface a necessary ingredient for severe thunderstorms?

More latent heat energy available as storm

An air mass thunderstorm is most intense during

mature stage

The approximate lifetime of an individual thunderstorm cell is about

20-30 minutes

Thunderstorms are most common in

Southern Mississippi

Tornadoes are most frequent during the

Late spring and early summer when warm and cold air often clashes

Tornadoes most often move toward what direction


At what time of day is an air mass thunderstorm more likely to develop?

Mid- afternoon

Heat Lightning

Occurs more then 20km away from observer

Downdrafts totally dominate this stage of a thunderstorm

Dissipating stage

This type of cloud brings thunderstorms

Cumunolimbus clouds

If you see lightning and then hear the thunder 10 seconds later

3300 meters

How many deaths did the deadliest U.S. hurricane cause


A hurricane must have sustained wind speeds of at least

65 knots, 74 mph

Western pacific hurricanes are called


Hurricanes in the Indian Ocean


What stages do hurricanes get named

35-65 knots Tropical storm

When the entire alphabet of names is used they resort to

Greek alphabet

When winds do not exceed 37 mph

Tropical Depression

What is the single greatest advance for observing cyclones?

Satellite Imagery

Strongest category on Saffir-Simpson scale


Hurricanes often develop in late summer when waters reach

27 C

Why don't hurricanes develop near the equator

No coriolis effect

Why do surface wind speeds increase toward the center of a hurricane?

Conservation of angular momentum

Why do hurricanes in the Atlantic move toward the west during early stages?

Prevailing winds from the east

Hurricanes form in the South Atlantic


Approximate diameter of a mature hurricane

Around 300km+

Why is the eye region of a hurricane largely free of precipitation and clouds?

Subsiding air

What causes the winds of a hurricane to be so fast?

Strong pressure gradient

What part of the hurricanes produces fastest winds and storm surges?

Vertical Wall

Why do hurricanes decline over land?

Friction. lack of warm moist air

The eye of a hurricane

highest wind speeds and warmest temperature

About what percent of hurricanes that make landfall produce a tornado

Less then 1 percent

Which months do hurricanes peak in North atlantic?


This scale measures hurricane intensity


Hurricanes form in this latitude

5-20C latitude

Most important tool for detecting and monitoring hurricanes is

Doppler radar

GPS is used for

determined vertical pressure, temperature, humidity over an area

Problem with issuing a hurricane

80 to 90 percent living in these areas have not experienced a hurricane

Secondary rainbows result from

double internal reflection

How many refractions occur for a rainbow


Which of these are the primary optical phenomena causing a rainbow?

Refraction and reflection

The speed of light in water is

Fastest for red light

Rainbows are always seen with the sun


The phenomenon that results from the speed of light changing as it passes into different substances


If light enters a transparent medium at a right angle, what change occurs

Slows down, and wavelength becomes shorter

Which substance has the greatest index of refraction


Reflection, refraction, and diffraction all cause light to change its


The speed of light in space is

3 million meters per second

The property of light that causes your arm to look bent when it is submerged in water is called


The "wet area" or water surface mirage as seen on a highway occurs when

cold air is over hot water

A layer of very warm, low density air near the surface causes light to

Create an inferior mirage

Produced by refraction caused by ice crystals


Halo forms in association with

Moon and Sun

Before sunlight interacts with the atmosphere, its color is

No color

The moon appears larger when it is low on the horizon because

Optical illusion

To see a rainbow

Between the rain and the sun

Thunderstorms are electrified by

Ice particles and supercooled water form above freezing level. Negative cloud charge

Tornadoes rotate this way in Northern hemisphere

Counter-clock wise

Hurricanes re-curve because

prevailing wind and environmental flow

Hurricane in easy Asia


Hurricane in Pacific


Heat lightning is caused by

distant storms

lifetime of a single cell

20-30 mins

Maximum wind speeds ever observed in a tornado


Key ingredients that determine storm type are

moisture, lift, and instability

Squall lines form ahead of

cold fronts

El Nino is

Unseasonal warming of Pacific Ocean and area around equator

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