Deck 14: Thunderstorms and Tornadoes

Question 1

The most likely time for an ordinary thunderstorm to form is

A) just after sunrise.
B) just before sunrise.
C) around midnight.
D) late afternoon.
E) at noon.

Answer 1

D

Question 2

Many flash floods,including those that occurred in Rapid City,South Dakota,and in Colorado's Big Thompson Canyon,are the result of thunderstorms that

A) contain no lightning.
B) form in a dry air mass.
C) move slowly.
D) have weak or non-existent downdrafts.

Answer 2

C

Question 3

Thunderstorms that produce tornadoes

A) have very little cloud-to-ground lightning.
B) have updraft velocities that exceed 100 miles per hour.
C) have rotating updrafts.
D) will not produce hail.

Answer 3

C

Question 4

Which of the following would you not expect to observe during the passage of a gust front?

A) gusty winds
B) rising surface pressures
C) increase in temperatures
D) wind shift

Question 5

An ordinary thunderstorm is most intense during the ____ stage.

A) mature
B) multicell
C) cumulus
D) dissipating

Question 6

Squall lines generally do not form

A) behind a cold front.
B) when the air aloft develops waves downwind from a cold front.
C) along a dry line.
D) in the warm sector where warm,dry air meets warm,humid air.
E) ahead of an advancing cold front.

Question 7

Lightning may occur

A) within a cloud.
B) from a cloud to the ground.
C) from one cloud to another cloud.
D) all of the above

Question 8

Most squall line thunderstorms form

A) in advance of a cold front.
B) along a cold front.
C) behind a cold front.
D) in advance of a warm front.
E) along an occluded front.

Question 9

During the summer,what conditions prevail near the surface over the Great Plains that help a hailstone survive as ice all the way to the ground?

A) a warm,shallow layer of dry air
B) a warm,thick layer of moist air
C) a cold,shallow layer of dry air
D) a cold,thick layer of moist air
E) a warm,shallow layer of moist air

Question 10

Which figure comes closest to the estimated number of thunderstorms that occur each year throughout the world?

A) 2,000
B) 40,000
C) 100,000
D) 600,000
E) 14,000,000

Question 11

The initial stage of an ordinary thunderstorm is the

A) mature stage.
B) dissipating stage.
C) cumulus stage.
D) multicell stage.

Question 12

Downdrafts spread throughout a thunderstorm during the ____ stage.

A) cumulus
B) dissipating
C) precipitating
D) developing

Question 13

All thunderstorms require

A) hot,humid air.
B) divergence of the air aloft.
C) lifting along some barrier such as a mountain or front.
D) surface heating.
E) rising air.

Question 14

Distant lightning that is so far away you cannot hear the thunder is called

A) sheet lightning.
B) heat lightning.
C) false lightning.
D) St.Elmo's fire.
E) auroral lightning.

Question 15

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

A) lightning neutralizes all the electrical charge in the cloud.
B) when all the precipitation particles in the cloud turn to ice.
C) when the downdraft spreads throughout the cloud and cuts off the updraft.
D) when solar heating at the ground begins to decrease.

Question 16

An ordinary thunderstorm is a

A) thunderstorm that does not produce lightning or thunder.
B) thunderstorm that has a tilted updraft and downdraft.
C) scattered or isolated storm that is not severe.
D) thunderstorm that does not produce hail.

Question 17

The downdraft in an ordinary thunderstorm is created mainly by

A) the melting of snow in the anvil.
B) electrical attraction between the cloud and ground.
C) the release of latent heat as water in the cloud freezes.
D) evaporating raindrops that make the air cold and heavy.
E) upper level wind motions.

Question 18

Severe thunderstorms are different from ordinary thunderstorms in that severe thunderstorms

A) contain thunder and lightning.
B) have an anvil.
C) contain hail.
D) have a strong updraft and downdraft.
E) have a tilted updraft in the mature stage.

Question 19

A small thunderstorm cloud with virga falling out of its base and blowing dust at the ground could warn of a severe hazard to an airplane because

A) this could be the first indication of a tornado.
B) it is likely that hail will soon begin to fall.
C) this could indicate an intense downdraft or microburst.
D) the airplane could be struck by lightning.

Question 20

The wind shear associated with several major airline crashes is believed to have been caused by

A) microbursts.
B) dry lines.
C) the jet stream.
D) mesocyclones.

Question 21

Which of the following statements about tornadoes is correct?

A) All tornadoes rotate in a counterclockwise direction.
B) Tornadoes never strike the same place twice.
C) All tornadoes make a distinction roar.
D) The United States has more tornadoes that any other country in the world.

Question 22

Electrons

A) are negatively charged.
B) are positively charged.
C) carry no charge.
D) can carry either positive or negative charge.

Question 23

If a tornado is rotating in a counterclockwise direction and moving toward the northeast,the strongest winds will be on its ____ side.

A) southwestern
B) southeastern
C) northeastern
D) northwestern

Question 24

In a typical tornado the winds are usually not much more than ____ miles per hour.

A) 25
B) 50
C) 100
D) 200

Question 25

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

A) negatively,negatively
B) negatively,positively
C) positively,positively
D) positively,negatively

Question 26

You are generally safe inside an automobile during a lighting storm because

A) the car's radio antenna will act as a lightning rod:
B) the rubber tires insulate you from the ground.
C) metal cars do not become electrically charged.
D) the metal car body will carry the lightning current around the passengers inside.

Question 27

A cloud-to-ground lightning discharge will sometimes appear to flicker.This is because

A) you are able to see the separate steps of the stepped leader.
B) you are able to distinguish separate return strokes.
C) the bright light causes you to blink.
D) of refraction caused by turbulent thunderstorm winds.

Question 28

If you see a lightning stroke and then,15 seconds later,hear the thunder,the lightning is about ____ miles away.

A) 45
B) 15
C) 5
D) 3

Question 29

Which of the following is the most accurate description of the principle of a lightning rod?

A) The lightning rod acts to discharge the thunderstorm.
B) The lightning rod intercepts the lightning and safely carries the lightning current around the object it protects.
C) Lightning rods have been used since the 1700s,but the principle of their operation is not known.
D) Positive charge induced in the lightning rod repels the negative charge in an approaching step leader.

Question 30

Thunder is caused by

A) the collision between two thunderstorms with opposite electrical charge.
B) the rapid heating of air surrounding a lightning channel.
C) the explosion that occurs when + and - charge collide and neutralize each other.
D) turbulent wind motions inside the thunderstorm.

Question 31

In the United States,tornadoes are most frequent during the ____,and least frequent during the ____.

A) summer,fall
B) spring,winter
C) spring,fall
D) summer,winter
E) winter,fall

Question 32

When caught in a thunderstorm in an open field,the best thing to do is to

A) run for cover under the nearest tree.
B) lie down flat on the ground.
C) crouch down as low as possible while minimizing contact with the ground.
D) remove all metallic objects from your pockets.

Question 33

The funnel cloud characteristic of a tornado is principally formed by

A) condensation of water vapor in air drawn into the low pressure core of the tornado.
B) dust and dirt picked up from the atmosphere.
C) clouds being funneled by downward air currents coming out of a cumulonimbus cloud.
D) water drawn up from the sea surface into the cloud.
E) gaseous products from intense lightning activity within the tornado.

Question 34

An important principle in the electrification of a cumulonimbus cloud is that

A) raindrops are always positively charged.
B) supercooled water is always negatively charged.
C) ice crystals are always negatively charged.
D) there is a net transfer of positive ions from a warmer object to a colder object.

Question 35

Thunder will not occur

A) without lightning.
B) in wintertime thunderstorms.
C) in thunderstorms over the ocean.
D) when a thunderstorm is producing precipitation.

Question 36

The electrification of a cumulonimbus cloud appears to involve

A) graupel or hailstones.
B) supercooled cloud droplets.
C) ice crystals.
D) all of the above

Question 37

Most tornadoes move from

A) northwest to southwest.
B) southwest to northeast.
C) south to north.
D) southeast to northwest.

Question 38

Which of the following factors is most important in determining the strength of a tornado?

A) diameter
B) air temperature
C) duration
D) central pressure

Question 39

A typical diameter of a tornado would be

A) 50 meters.
B) 250 meters.
C) 1,000 meters.
D) 2,500 meters.
E) 4,000 meters.

Question 40

The most frequent time of day for tornadoes to form is in the

A) early morning just after sunrise.
B) late morning just before noon.
C) evening just after sunset.
D) afternoon.
E) middle of the night.

Question 41

Compare some damaging straight-line winds with tornado winds.Which do you think are more destructive?

Question 42

Tornadoes are usually observed

A) behind cold fronts.
B) on the windward side of mountains.
C) near large bodies of water.
D) along occluded fronts.
E) ahead of cold fronts.

Question 43

Supercell thunderstorms ____ become severe.

A) rarely
B) occasionally
C) often
D) always

Question 44

Strong vertical wind shear

A) does not play an important role in the development of severe thunderstorms.
B) inhibits the formation of severe thunderstorms.
C) helps thunderstorms to become severe.

Question 45

List and discuss some of the atmospheric conditions that are needed for a thunderstorm to develop.

Question 46

Where do thunderstorms form most frequently in the US? Why is this the case? Is this also where most tornadoes occur? Explain.

Question 47

At home,when confronted with an approaching tornado,you should

A) open the windows right away.
B) grab a video camera and start filming.
C) listen to see whether the tornado has an audible roar.
D) seek shelter immediately.

Question 48

The Enhanced Fujita Scale for classifying tornado strength is based on

A) multiple damage indicators.
B) degree of damage.
C) atmospheric stability.
D) multiple damage indicators and the degree of damage.
E) none of the above

Question 49

List and describe the sequence of events that occur during a cloud-to-ground lightning discharge.

Question 50

Do invisible tornadoes exist? Why or why not?

Question 51

List and describe the stages of development of an ordinary thunderstorm.About how long does a single ordinary thunderstorm cell last?

Question 52

In what ways are multicell thunderstorms different from ordinary thunderstorms? What are some of the meteorological or atmospheric conditions that favor the development of multicell thunderstorms?

Question 53

What is a squall line? Where would you expect squall lines to form?

Question 54

Damage to structures inflicted by tornadoes can be caused by

A) flying debris.
B) the tornadoes high winds.
C) the drop in air pressure as a tornado moves overhead.
D) the drop in air pressure above a roof as high winds blow over it.
E) all of the above

Question 55

After a tornado is spotted,

A) a tornado watch is issued.
B) its direction of movement is carefully monitored by aircraft.
C) a tornado warning is issued.
D) hail begins to fall from the cloud.
E) attempts may be made to change its direction of movement.

Question 56

In a region where severe thunderstorms with tornadoes are forming,one would not expect to observe

A) a strong ridge of high pressure over the region.
B) a dry tongue of cold air between the 700 and 500 mb levels.
C) the polar jet stream above the region.
D) moist warm air moving north at about the 850 mb level.

Question 57

The signal detected by a Doppler radar is

A) a radiowave emitted by lightning.
B) a soundwave produced by thunder.
C) a radiowave reflected by precipitation.
D) a soundwave produced by wind shear.

Question 58

Where does the energy contained in a mature thunderstorm come from?

Question 59

In an eastward moving thunderstorm,the most likely place for a tornado to develop is in the ____ part of the storm.

A) northeast
B) southeast
C) northwest
D) southwest

Question 60

What is wind shear? Why does wind shear represent a hazard to aviation?

Question 61

What makes a tornado-producing thunderstorm different from other thunderstorms?

Question 62

The fact that thunder sometimes sounds like a loud crash or peal,and other times sounds like a dull rumble,has nothing to do with the intensity of the lightning strike that produced the thunder.Explain why.

Question 63

How does a supercell thunderstorm differ from a multicell thunderstorm?

Question 64

The region of greatest tornado activity shifts northward from early spring to summer.Why does this occur?

Question 65

Most tornadoes move from the southwest toward the northeast.Why is this true?