ch.10

7) Which of the following U.S. states experiences the most thunderstorms each year? A) Florida B) Texas C) Colorado D) Oklahoma

A) Florida

44) The greatest number of deaths associated with thunderstorms result from: A) flash flooding. B) lightning. C) hail. D) tornadoes.

A) flash flooding.

49) It is impossible to warn people of every lightning flash because: A) it strikes so frequently and in so many places. B) it kills few people compared to the other types of severe weather, so it isn't studied as much. C) scientists don't understand exactly how it forms. D) people are only struck by lightning a few times each decade, so most don't listen to warnings.

A) it strikes so frequently and in so many places.

16) Which of the following is likely during the mature stage of a thunderstorm? A) lightning B) light winds C) light precipitation D) no precipitation

A) lightning

15) At what time of day is an air-mass thunderstorm more likely to develop? A) midafternoon B) midnight C) midmorning D) pre-dawn

A) midafternoon

48) In the United States, a mesoscale convective complex is most likely to develop in: A) the Great Plains. B) the Pacific Northwest. C) New England. D) the Gulf of Mexico.

A) the Great Plains.

40) What does the term mesocyclone refer to in reference to a tornado? A) the rotation of the updraft in the parent thunderstorm B) a high-altitude tornado C) a false-alarm tornado warning D) a very large tornado

A) the rotation of the updraft in the parent thunderstorm

64) The diameter of a typical tornado funnel cloud would be: A) 50 - 100 meters. B) 150 - 600 meters. C) 1000 - 2500 meters. D) 3000 meters

B) 150 - 600 meters.

57) Because of the tremendous pressure gradient associated with a strong tornado, maximum winds approach ________ miles per hour. A) 100 B) 300 C) 600 D) 1000

B) 300

53) Which of the following demonstrates the correct order of the phases involved in a lightning stroke? A) Step leaders, return stroke, separation of charges, flow of negative charge into ground, dart leader B) Charge separation, step leaders, return stroke, flow of negative charge into ground, dart leader C) Dart leader, charge separation, flow of negative charge into ground, step leaders, return stroke D) Charge separation, dart leader, step leaders, flow of negative charge into ground, return stroke

B) Charge separation, step leaders, return stroke, flow of negative charge into ground, dart leader

51) Which type of lightning is least likely? A) within the same cloud B) cloud-to-Earth C) cloud-to-cloud

B) cloud-to-Earth

63) Of the following states, which is struck by the largest number of tornadoes? A) North Carolina B) Ohio C) Oklahoma D) New Mexico E) North Dakota

C) Oklahoma

41) ________ are relatively narrow, elongated bands of thunderstorms that develop in the warm sector of a middle-latitude cyclone, usually in advance of a cold front. A) Roll clouds B) Mesocyclones C) Squall lines D) Supercells

C) Squall lines

1) The term cyclone is BEST defined as: A) a hurricane. B) a violent tornado. C) any circulation around a low-pressure center. D) a storm that develops over an ocean.

C) any circulation around a low-pressure center.

24) In the development of a thunderstorm, sharp and cool gusts beginning at the surface are characteristic in the ________. A) cumulus stage B) dissipating stage C) mature stage

C) mature stage

65) Tornadoes most often move toward what direction? A) southeast B) west C) northeast D) southwest E) northwest

C) northeast

56) Which of the following should have the steepest pressure gradient? A) middle-latitude cyclone B) hurricane C) tornado D) typhoon

C) tornado

8) Thunderstorms form when ________, humid air rises in a(n) ________ environment. A) warm; stable B) cold; unstable C) warm; unstable D) cold; stable

C) warm; unstable

6) About how many thunderstorms take place on Earth every day? A) 300 B) 1300 C) 5000 D) 45,000

D) 45,000

42) A squall line is most likely to develop where? A) in the middle of a cP air mass B) along a warm front C) along a cold front D) along a dryline in the warm sector of a mid-latitude cyclone

D) along a dryline in the warm sector of a mid-latitude cyclone

3) Thunderstorms can be associated with these weather activities: A) cyclones. B) hurricanes. C) tornadoes. D) cyclones, hurricanes, and tornadoes.

D) cyclones, hurricanes, and tornadoes.

60) Which of the numbers listed below best represents the percentage of thunderstorms that produce tornadoes? A) about 10 percent B) slightly more than 50 percent C) nearly 25 percent D) less than 1 percent

D) less than 1 percent

52) The terms leader, flash, and stroke are used when describing: A) squall line formation. B) the stages of a thunderstorm. C) the passage of a hurricane. D) lightning. E) a tornado.

D) lightning.

20) An air mass thunderstorm is most intense during the ________ stage. A) multicell B) cumulus C) dissipating D) mature

D) mature

28) Thunderstorm tops most likely occur: A) in the lower troposphere. B) in the middle stratosphere. C) in the mesosphere. D) near the tropopause.

D) near the tropopause.

54) "Heat lightning": A) is actually a display of the northern lights. B) is also called "ball lightning." C) is brighter than ordinary lightning. D) occurs more than 20 kilometers from the person observing it.

D) occurs more than 20 kilometers from the person observing it.

69) Conventional radar measures: A) raindrop motion. B) raindrop size. C) raindrop and snowflake motion. D) rainfall intensity. E) cloud droplet numbers.

D) rainfall intensity.

36) Some of the most dangerous weather is produced by a type of thunderstorm called a(n): A) gust front. B) updraft C) roll cloud. D) supercell.

D) supercell.

38) A roll cloud forms in association with which other common thunderstorm feature? A) the precipitation B) the anvil C) the updraft D) the gust front

D) the gust front

9) Thunderstorms and large cumulus clouds are characteristic of: A) all polar air masses. B) isothermal lapse rates. C) all warm fronts. D) unstable air. E) stable air.

D) unstable air.

26) This type of cloud brings thunderstorms. A) cumulus B) altostratus C) nimbostratus D) stratocumulus E) cumulonimbus

E) cumulonimbus

4) A tornado is a small, very intense example of the: A) Coriolis effect. B) anticyclone. C) jet stream. D) geostrophic wind. E) cyclone.

E) cyclone.

13) Why is strong heating of the ground by the Sun associated with thunderstorms? A) reduces the relative humidity B) reduces the dew point C) increases the wind speed D) increases the pressure gradient E) leads to greater instability

E) leads to greater instability

70) Doppler radars: A) detect lightning strokes. B) have much greater range than conventional radars. C) detect condensation nuclei. D) show the motion of air in clear areas. E) show the motion of precipitation particles.

E) show the motion of precipitation particles.

101) Destruction caused by a tornado is primarily due to the large pressure drop as the funnel passes over.

FALSE

102) Weak tornadoes (EF0-EF1) are responsible for the majority of tornado deaths because they are far more common than stronger tornadoes (EF2 and above).

FALSE

103) About 50 percent of North American tornadoes are classified as violent (EF4-EF5).

FALSE

104) Radar detects a thunderstorm by measuring the electrical discharges within the cloud.

FALSE

105) A tornado warning is issued by the National Weather Service when conditions are favorable for tornado development.

FALSE

76) Entrainment refers to the tendency of thunderstorms to form in a line-like pattern or sequence.

FALSE

77) Most precipitation from thunderstorms originates through the collision-coalescence process.

FALSE

79) The airflow pattern aloft is not usually related to severe thunderstorm development.

FALSE

91) Cloud-to-ground lightning results in a flow of electrons from the ground to the cloud.

FALSE

92) Thunder generates lightning.

FALSE

96) When tornadoes develop it is usually in association with air-mass thunderstorms.

FALSE

97) If a severe thunderstorm produces large hail, it will not produce a tornado.

FALSE

Divergence in the upper-level jet stream hinders the formation of severe thunderstorms.

FALSE

During the dissipating stage of a thunderstorm, the downdraft is weaker than the updraft.

FALSE

It is generally considered safe to talk on the phone during a lightning storm, as long as it is a corded telephone.

FALSE

Lightning always occurs between a cloud and the ground.

FALSE

Lightning only occurs under the central part of a thunderstorm cloud.

FALSE

On average, tornadoes kill more people every year in the United States than any other severe weather phenomenon.

FALSE

106) Doppler radar can detect motion directly.

TRUE

78) Mountainous regions, such as the Rockies in the West and the Appalachians in the East, experience a greater number of air-mass thunderstorms than do the Plains states.

TRUE

80) Large hail is generally associated only with severe thunderstorms.

TRUE

81) The anvil top of a thunderstorm often marks the beginning of the stratosphere.

TRUE

93) A long lightning flash at some distance from the observer produces the thunder we hear as a rumble.

TRUE

98) A mesocyclone often precedes tornado development.

TRUE

99) The central United States sees more tornadoes than any other region in the world.

TRUE

A developing tornado is called a funnel cloud until it makes contact with the surface.

TRUE

A squall line with severe thunderstorms can also form along a boundary called a dryline, a narrow zone along which there is an abrupt change in moisture.

TRUE

An airplane flown by an untrained pilot is likely to crash if it flies through a downburst.

TRUE

Temperature inversions (stable layers) in air layers above the ground can contribute to thunderstorm development.

TRUE

The term "cyclone" simply refers to the circulation around any low-pressure center, no matter how large or intense it is.

TRUE

66) Why do most tornadoes tend to travel in the same general direction? A) Because of their clockwise rotation. B) They generally occur in a zone of southwest winds. C) They have an intense pressure gradient force. D) Tornadoes often occur to the east of the center of a midlatitude cyclone.

B) They generally occur in a zone of southwest winds.

10) In which of the following places are thunderstorms most common? A) central Nevada B) central Florida C) northern Wisconsin D) west of Hudson Bay (Canada) E) The occurrence of thunderstorms at all of these places should be about the same.

B) central Florida

50) Extreme evaporative cooling can sometimes produce explosions of straight-line winds called: A) gust fronts .B) downbursts. C) tornadoes. D) air bombs.

B) downbursts.

45) Hurricanes and thunderstorms can sometimes cause local floods that are short-lived but high volume. These are called: A) rapid floods B) flash floods C) 100-year floods D) surge floods

B) flash floods

43) Over the last 30 years, which of these has caused the FEWEST weather related deaths on average in the U.S.? A) lightning B) hurricanes C) tornadoes D) floods

B) hurricanes

22) Downdrafts and updrafts found side by side relate to the ________ in the development of a thunderstorm. A) dissipating stage B) mature stage C) cumulus stage

B) mature stage

39) The leading edge of a gust front is frequently associated with: A) heavy precipitation. B) the development of a new cumulonimbus cloud. C) tornadoes. D) hail.

B) the development of a new cumulonimbus cloud.

29) An overshooting top means that: A) a thunderstorm will definitely produce a tornado B) the thunderstorm has very strong updrafts causing the cloud to grow into the stratosphere C) the thunderstorm is dissipating. D) lightning strikes will be especially intense.

B) the thunderstorm has very strong updrafts causing the cloud to grow into the stratosphere

59) Which of the following statements is not true of tornadoes? A) generally move from the southwest toward the northeast B) usually occur along the warm front of a midlatitude cyclone C) most common in the Midwest and Great Plains D) associated with cumulonimbus clouds E) occur most frequently in the spring of the year

B) usually occur along the warm front of a midlatitude cyclone

2) The circulation in the immediate vicinity of a thunderstorm is: A) anticyclonic. B) variable and gusty. C) cyclonic. D) calm.

B) variable and gusty.

Thunderstorms are not always associated with cyclonic activity.

TRUE

27) About what percent of thunderstorms in the United States become severe? A) 10% B) 20% C) 25% D) 50%

A) 10%

61) Why do most tornadoes in the central U.S. occur during the spring months? A) Air-mass contrasts are greatest. B) Divergence of air aloft is greatest. C) Solar energy is a maximum. D) Surface air is most humid. E) Upper-air temperatures are warmest.

A) Air-mass contrasts are greatest.

14) Why are thunderstorms most likely to occur in the afternoon and early evening? A) Atmosphere is most unstable at that time. B) Upper-level winds are too fast at night and in morning. C) Water-vapor contents are too low at night. D) It takes all day for them to mature. E) Lower atmosphere is too unstable in the morning.

A) Atmosphere is most unstable at that time.

5) Tornadoes and midlatitude cyclones are similar in that: A) both are areas of low pressure. B) both are most common and well-developed in the winter season. C) both have conspicuous surface fronts. D) both form in the trade-wind belt.

A) both are areas of low pressure.

23) Updrafts dominance relate to the ________ in the development of a thunderstorm. A) cumulus stage B) dissipating stage C) mature stage

A) cumulus stage

12) Generally there are three stages involved in the development of thunderstorms. They are: A) cumulus stage, mature stage, and dissipating stage. B) cumulus stage, mature stage, and deconstructing stage. C) cumulus stage, adolescent stage, and dissipating stage. D) cumulus stage, dissipating stage, and deconstructing stage.

A) cumulus stage, mature stage, and dissipating stage.

25) Downdrafts totally dominate the ________ in the development of a thunderstorm. A) dissipating stage B) mature stage C) cumulus stage

A) dissipating stage

21) An air mass thunderstorm rarely lives long enough to create very severe weather because: A) the downdrafts quickly become strong enough to stop the updraft and influx of moisture to the storm. B) the atmosphere is generally fairly stable when these storms develop. C) there is rarely enough moisture available to keep the storm alive for longer than 30 minutes. D) wind shear causes the storm's updraft to become tilted.

A) the downdrafts quickly become strong enough to stop the updraft and influx of moisture to the storm.

47) Drylines are capable of producing thunderstorms because: A) the dry air mass forces the moist air mass to rise. B) the moist air mass lifts the dry air mass. C) there is an abrupt change in temperature across the dryline. D) the dry air mass is unstable and rising.

A) the dry air mass forces the moist air mass to rise.

68) The Enhanced Fujita scale is based on: A) the level of damage caused by a tornado. B) the measured wind speeds inside a tornado. C) the pressure gradient across the diameter of a tornado. D) the frequency of lightning strikes concurrent with the tornado.

A) the level of damage caused by a tornado.

17) What is entrainment? A) the process of cool, dry air being pulled into a thunderstorm by the downdraft B) warm, moist air fed into a thunderstorm by the updraft C) rotation from the parent cloud transferring into a tornado D) a line of thunderstorms, one feeding into the next

A) the process of cool, dry air being pulled into a thunderstorm by the downdraft

71) Which association is incorrect? A) tornado watch — a tornado has been sighted on the ground B) downdraft — precipitation C) anvil - front of the thunderstorm D) mesocyclone — region of tornado formation

A) tornado watch — a tornado has been sighted on the ground

67) The Enhanced -Fujita Intensity Scale (EF-scale) is applied to: A) tornadoes. B) typhoons. C) lightning. D) thunderstorms.

A) tornadoes.

58) Multiple-vortex tornadoes help explain: A) why one building is destroyed and the one next to it is untouched. B) why tornadoes are so short lived. C) why some tornadoes never touch the ground. D) what EF rank a tornado should have.

A) why one building is destroyed and the one next to it is untouched.

62) Tornadoes are most frequent during the: A) month of September. B) January-March period. C) April-June period. D) October-December period. E) July-August period.

C) April-June period.

37) The gust front occurs: A) during the development of thunderstorm clouds. B) near the anvil part of a thunderstorm cloud. C) at the leading edge of a thunderstorm downdraft. D) on the lee shore of the Great Lakes.

C) at the leading edge of a thunderstorm downdraft.

46) A dryline generally forms between which two air masses? A) mP and mT B) cP and cT C) cT and mT D) cP and mT

C) cT and mT

19) Why is very humid air near the surface a necessary ingredient for severe thunderstorms? A) High humidity strengthens the cold front. B) High humidity makes the air more dense. C) High humidity makes the rising air cool more rapidly. D) Lapse rates are larger in humid air. E) More latent heat is then available as energy for the storm.

E) More latent heat is then available as energy for the storm.

18) What causes the dissipating stage of a thunderstorm? A) converging surface winds B) loss of radiant energy from cloud top C) release of latent heat within the cloud D) converging winds aloft E) spreading downdraft cuts off air inflow

E) spreading downdraft cuts off air inflow

11) The greatest proportion of thunderstorms occurs in the: A) middle latitudes. B) subtropics. C) polar regions. D) subarctic regions. E) tropics.

E) tropics.

55) If you see lightning and then hear the associated thunder 10 seconds later, the lightning flash was about ________ mile(s) away. A) three B) four C) one D) five E) two

E) two

100) A thunderstorm's direction of movement over the ground is determined by the gust front.

FALSE

Squall lines are easily recognized because of their unique nimbostratus clouds.

FALSE

The primary force causing the fast winds of a tornado is electrical.

FALSE

The vast majority of cyclones are hurricanes and tornadoes.

FALSE