Final exam- Weather and Climate

Regions where air masses originate are known as

source regions

The origin of cP and cA air masses that enter the United States is

Northern Canada and Alaska.

A good source region for an air mass would be ____.

generally flat areas of uniform composition with light surface winds

Which of the following statements is most plausible?

In winter, cA source regions have lower temperatures than cP source regions.

Compared to an mP air mass, mT air is

warmer and moister

An air mass is characterized by similar properties of ____ and ____ in any horizontal direction.

temperature; humidity

One would expect a cP air mass to be

Cold and Dry

Which air mass would show the most dramatic change in both temperature and moisture content as it moves over a large body of very warm water?

cP in winter

The lake effect occurs when a(n) ____ air mass moves over a ____ body of water.

cP; warm

The designation for a cool, moist air mass is ____.

mP

What type of air mass would be responsible for hot, muggy summer weather in the eastern half of the United States?

mT

The air mass with the highest actual water vapor content is

mT

On a weather map, the transition zone between two air masses with sharply contrasting properties is marked by ____.

A Front

The word frontogenesis on a weather map would mean that ____.

a front is regenerating or strengthening

A dryline is ____.

both a dew point front and a boundary marking a strong horizontal change in atmospheric moisture

If either a cold front or a warm front stops moving, what does it become?

A Stationary Front

Alternating lines of blue and red on a surface weather chart indicate a(n) ____.

A Stationary Front

A stationary front does not move because ____.

the winds blow against each other and are of equal strength

Before the passage of a cold front the pressure normally ____, and after the passage of a cold front the pressure normally ____.

Drops; rises

Squall lines most often form ahead of a ____.

Cold Front

A "back-door" cold front best describes which of the following situations?

A cold front that moves into New England from the Atlantic Ocean

At a warm front, the warm air ____.

Rises and Cools

During the winter as you travel toward a warm front, the most likely sequence of weather you would experience is

snow, sleet, freezing rain, and rain

Occluded fronts may form when ____.

a cold front overtakes a warm front

If an area is described as a "good air mass source region," what information can you give about it?

The area would be flat and uniform with low wind speeds.

Explain why barometric pressure usually falls with the approach of a cold front.

This is because the cold front causes warm air to rise, leading to lower surface pressure.

An _____ is an extremely large body of air whose properties of temperature and humidity are fairly similar in any horizontal direction at any given altitude.

Air Mass

All thunderstorms require ____.

Rising Air

The initial stage of an ordinary thunderstorm is the ____.

Cumulus Stage

Ordinary thunderstorms only last about one hour and begin to dissipate when ____.

when the downdraft spreads throughout the cloud and cuts off the updraft

An ordinary thunderstorm ____.

is a scattered/an isolated storm and normally not severe

Downdrafts tend to dominate during the ____ stage.

Dissipating

An ordinary thunderstorm is most intense during the ____ stage.

Mature

The most likely time for an ordinary thunderstorm to form is ____.

Late afternoon

Which of the following is NOT a trigger needed to start air moving upward and thus causing thunderstorms?

Cool air rising along a frontal zone

Thunderstorms that produce tornadoes ____.

Have rotating updraft

Drier air from around the cloud is being drawn into it in a process called

entrainment

Why the downdraft in a thunderstorm is cold? Think about two reasons.

Two reasons why downdraft from a thunderstorm is cold is from evaporation cooling and when rain falls it is colder than the surrounding air so as it falls it cools the air.

When the cold downdraft reaches Earth's surface, it pushes outward in all directions, producing a strong _____ that represents the leading edge of the _____ air.

Gust Front; outflowing

A single ordinary cell thunderstorm may go through its three stages in

One hour or less

Thunderstorms that contain a number of cells, each in a different stage of development, are called _____ thunderstorms.

Multi-cell

Describe the formation of a multi-cell thunderstorm.

The formation of a multi-cell thunderstorm is produced when strong wind shear causes the updraft to rise above the downdraft creating new storm cells.

As warm, moist air rises along the forward edge of the gust front, a ____ cloud may form.

Shelf

Multicell thunderstorms may form as a line of thunderstorms, called a ____.

Squall Line

A squall line usually forms behind a cold front.

False

Thunderstorms are much less prevalent in dry climates.

True

Where does the highest frequency of thunderstorms occur in the United States? Why there?

The highest frequency of thunderstorms occur in the south eastern portion of the United States more specifically Florida because of the warm moist air coming from the Gulf of Mexico.

Flooding may also occur when thunderstorms move quickly, but keep passing over the same area, a phenomenon called thunderstorm _____ .

Training

If you see lightning and 10 seconds later you hear thunder, how far away is the lightning stroke?

2 miles

The upper part of a thunderstorm cloud is normally ____ charged, and the middle and lower parts are ____.

positively; negative

A storm that forms at middle and high latitudes is called a ______ storm

mid-latitude cyclonic

Norwegian Meteorologists developed a ______ theory of a developing wave cyclone describing how a mid-latitude cyclone progresses through the stages of _____ ,______ , and ______ , and the development of _______ along the polar front.

Polar Front; Birth; Growth; Decay; Weather

On a surface weather map that shows an open wave cyclone, the warm sector can be observed ____.

between the cold and warm fronts

According to the model of the life cycle of a wave cyclone, the storm system is normally most intense ____.

when the system first becomes occluded

The development or strengthening of a middle latitude storm system is called ____.

cyclogenesis

If the flow of air into a surface low pressure area is greater than the divergence of air aloft, the surface pressure in the center of the low will ____.

Increase

In the polar front theory of a developing wave cyclone, energy for the storm is usually derived from an increase in surface winds, rising of warm air and sinking of cold air, and latent heat of condensation.

True

Which of the following is associated with rising air motions in a mid-latitude cyclone?

Convergence of air at the surface

A lee-side low forms ____.

on the downwind side of a mountain

A surface low pressure area with a deep upper-level trough to the west will tend to move toward the ____.

Northeast

When a deep upper-level trough is located to the east of a surface anticyclone, the surface anticyclone will tend to move toward the ____.

Southeast

When an upper-level low lies directly above a surface low, ____.

the surface low will probably weaken

For a surface storm system to intensify, the upper-level low (or trough) should be located to the ____ of the surface low.

West

Longwaves often ____, or even move ____.

remain stationary; retrograde

An upper-level trough that shows retrograde motion would be moving toward the ____.

West

Rossby waves are also known as ____.

Longwaves

Atmospheric shortwaves usually move from ____ at a speed that is ____ than longwaves.

West to east; Faster

Atmospheric shortwaves usually move ____ longwaves, and ____ when they move through a longwave ridge.

faster than; weaken

Since the Northern Hemisphere's polar jet stream is strongest and moves farther south in ____, we can see why mid-latitude cyclonic storms are better developed and move more quickly during the ____ months.

Winter; Colder

When viewed from above, the majority of North American tornadoes rotate clockwise about their central core of low pressure.

False

The majority of tornadoes have wind speeds of less than ___.

115 mi/hr

Some violent tornadoes may have winds exceeding ___.

250 mi/hr

The diameter of most tornadoes is between ___ and ___ m,

100; 600

The largest tornado on record is the tornado that occurred in western Oklahoma near El Reno on May 31, 2013 and spaned 2.6 miles.

True

Most tornadoes last only a few hours and have an average path length of about 40 miles.

False

The 1925 Tri-State (MO-IL-IN) Tornado is the longest official damage track on record with a path length of 619 miles.

False

The first stage of a tornado's life cycle is the _____ stage.

Dust-Whirl

The second stage of a tornado's life cycle is the ______ stage.

organization

The third stage of a tornado's life cycle is the ______ stage.

Mature

Damage caused by tornadoes normally is most severe in the ___ stage as the funnel reaches its greatest width and is almost vertical.

Third

Stage 4 is the _______ stage characterized by an overall decrease in the funnel's width and an increase in the funnel's tilt.

Shrinking

The final stage, called the ______ stage, usually finds the tornado stretched into the shape of a rope.

Decay

Tornadoes that form ahead of an advancing cold front tend to move from the ____.

southwest toward the northeast

No country experiences more tornadoes than ____.

The US

The tornado alley of the United States ____.

stretches from central Texas to Nebraska

The Central Plains region is susceptible to tornadoes because ____.

warm, humid surface air is overlain by cooler, drier air aloft

Violent tornadoes (with winds exceeding 180 knots) that contain smaller whirls rotating within them are called ____.

Multivortex tornadoes

On the Doppler radar screen, the rotating precipitation around a mesocyclone may appear as a(n) ____.

Hook Echo

A ______ is a rotating column of air that is connected to a cumuliform cloud over a large body of water.

Waterspout