Deck 11: Lightning, thunder, and Tornadoes

Question 1

The stepped-leader

A)moves downward in one continuous movement.
B)occurs after the formation of the return stroke.
C)creates the pathway for the flow of electrons.
D)has no similarities to a dart leader.

Answer 1

C

Question 2

________ lightning is extremely dangerous since it can occur from a relatively cloud-free sky.

A)Sheet
B)Heat
C)Anvil
D)Cloud-to-cloud

Answer 2

C

Question 3

Lightning is

A)when warm and cold air collide.
B)an indication of a high salt content in the air.
C)an indication that the atmosphere is virtually dust free.
D)a discharge of static electricity.

Answer 3

D

Question 4

Between the earth's surface and the ionosphere,

A)a large voltage difference occurs only when thunderstorms are present.
B)a large voltage difference always exists.
C)a very small voltage difference usually exists.
D)a very small voltage difference occurs only when thunderstorms are present.

Question 5

During a lightning event

A)a large quantity of electrons is transferred.
B)there is typically only one stroke.
C)the negative charge near the bottom of the cloud increases.
D)the air around the conducting channel is heated to temperatures up to 30,000 K.

Question 6

Cloud-to-cloud lightning makes up what % of all lightning?

A)20%
B)40%
C)60%
D)80%

Question 7

Lightning

A)never strikes twice at the same place.
B)strikes anywhere conductivity can be established.
C)never strikes water.
D)always strikes cedar trees.

Question 8

Most lightning discharges

A)originate in a cloud and travel toward the ground.
B)originate at the ground and travel toward a cloud.
C)occur within clouds.
D)originate within the ionosphere and travel to the ground.

Question 9

Worldwide,lightning results in how many deaths per year?

A)100
B)400
C)600
D)1000

Question 10

Thunder

A)moves at the speed of light.
B)always appears to the listener as a sharp clap.
C)is the cause of heat lightning.
D)results from the explosive expansion of air.

Question 11

The fair-weather electric field

A)results in only a small voltage difference between the ionosphere and the surface.
B)is maintained in large part through lightning.
C)distributes much electricity to the ground because air is a good conductor.
D)has its negative portion in the ionosphere.

Question 12

When a large number of runaway electrons accumulates in a small volume,the energy is released in a process called a

A)electron conveyer.
B)positive discharge.
C)runaway breakdown.
D)volumetric discharge.

Question 13

Sheet lightning

A)does not require a separation of charge.
B)is visible as sharp streaks of lightning arcing through the sky.
C)occurs when the electrical resistance in the air overcomes the voltage gradient within a cloud or between clouds.
D)accounts for the majority of all lightning events.

Question 14

Lightning can strike

A)below a thunderstorm cloud.
B)out of the anvil of a thunderstorm cloud.
C)from the side of the cloud.
D)all of these

Question 15

The thermoelectric-effect explanation for lightning

A)depends on the transfer of negative charge to hailstones.
B)cannot occur in a cloud that extends above the freezing level.
C)is dependent upon a magnetic field to induce charge separation in ice pellets.
D)depends upon ice crystals moving to the bottom of the cloud.

Question 16

Charge separation

A)results in the top of the cloud having a negative charge.
B)most often occurs in clouds that are not precipitating.
C)results in lightning only if the cloud extends above the freezing level.
D)is not explained by the thermoelectric effect.

Question 17

A typical cloud-to-ground lightning event consists of

A)a single electrical discharge.
B)a massive release of latent heat.
C)a combination of ionospheric discharge and wind shear.
D)several distinct steps that look to the human eye like a single lightning strike.

Question 18

This type of lightning extends up to 95 kilometers above the top of a thunderstorm,and it resembles a jellyfish:

A)sprite.
B)St. Elmo's fire.
C)ball lightning.
D)sheet lightning.

Question 19

Lightning that seems to occur without thunder is called

A)heat lightning.
B)silent lightning.
C)sheet lightning.
D)northern lightning.

Question 20

The sound of thunder caused by a lightning strike reaches your ears ________ the light from the lightning flash reaches your eyes.

A)before
B)at the same time as
C)after

Question 21

Give two reasons why lightning kills fewer people now than in the past.

Question 22

The induction explanation for lightning

A)is criticized by some scientists for not allowing enough time for the transfer of charge from ice crystals to hailstones.
B)assumes that the upper atmosphere has a positive charge.
C)assumes the transfer of electrons from ice pellets to ice crystals.
D)is criticized by some scientists for not taking into account that the electrical field is too strong.

Question 23

Thunder exhibiting a prolonged,rumbling sound

A)is likely originating from multiple lightning bolts.
B)is likely originating from different regions of a single lightning stroke.
C)indicates a reduced intensity of the associated lightning strike.
D)indicates a higher-temperature thunderstorm.

Question 24

Explain how the aviation industry safeguards modern aircraft against lightning.

Question 25

First describe the two main theories that describe charge separation.Then describe the formation and movement of a stepped-leader,return strokes,and dart leaders.

Question 26

Give two lightning safety rules.

Question 27

Explain why non-convertible automobiles are well protected against lightning.

Question 28

Cloud-to-ground lightning makes up what % of all lightning?

A)10%
B)20%
C)25%
D)50%

Question 29

Describe the four less-common types of lightning.

Question 30

In order to determine how far lightning is from your observation point

A)count the seconds from flash-to-bang and divide by ten.
B)count the seconds from flash-to-bang and divide by five to get miles.
C)listen to your AM radio and count the seconds from loud static to hearing the thunder and divide by ten.
D)count the seconds from flash-to-bang and divide by 30.

Question 31

Which of the following is NOT a part of the Earth's electric field?

A)positive charge in the upper atmosphere
B)negative charge on the surface
C)recharged by thunderstorm lightning
D)negative charge in the upper atmosphere

Question 32

This process of charge separation relies on the earth's electric field: ________.

Question 33

Which portion of the lightning process is the most visible?

A)charge separation
B)stepped leader
C)return stroke
D)dart leader

Question 34

The sound of thunder travels how many miles every 10 seconds?

A)1/2-mile
B)1 mile
C)2 miles
D)10 miles

Question 35

Cloud-to-cloud lightning is called ________.

Question 36

What % of the moisture that condenses within an air mass thunderstorm actually falls as precipitation?

A)5%
B)10%
C)20%
D)33%

Question 37

The Earth's electric field carries about ________ times the current of a North American home.

A)2
B)10
C)100
D)1,000

Question 38

Airplanes are struck by lightning

A)frequently.
B)only during clear-sky flights.
C)only during high altitude flights.
D)only during takeoff and landing.

Question 39

If you are outside in the presence of lightning and cannot take cover indoors,which of the following would be the safest course of action?

A)go to a low-lying area, crouch down and minimize your contact with the ground
B)lie face down in a ditch
C)seek shelter beneath a large tree
D)climb into the open back of a pickup truck

Question 40

The death toll from lightning in the United States has ________ since the 1920s.

Question 41

Supercell storms

A)are not readily visible on Doppler radar.
B)account for a majority of tornadoes.
C)do not exhibit any rotational aspects.
D)are larger than mesoscale convective complexes.

Question 42

Severe thunderstorms

A)have, by definition, wind speeds in excess of 90 miles per hour.
B)often appear in groups.
C)typically take place on the microscale.
D)rarely last more than an hour.

Question 43

Derecho winds are strongest when

A)upper-level winds are strong, because it spreads out the downdrafts.
B)upper-level winds are strong, because their momentum is carried to the surface.
C)upper-level winds are weak, because more wind shear is created.
D)upper-level winds are weak, because less wind shear is created.

Question 44

This image,showing storm radial velocity (the air motions taking place within a cloud)is especially useful in studying supercell storms: ________.

Question 45

Downdrafts that occupy the entire base of the cloud spell the end of this type of storm: ________.

Question 46

Doppler radar

A)measures the sound waves emitted by thunderstorms.
B)is used more extensively in Canada than in the United States.
C)uses ultraviolet light.
D)measures shifts in wavelengths of reflected electromagnetic radiation.

Question 47

Describe the physical properties and other important characteristics of a supercell storm.

Question 48

A common Doppler radar signature associated with a supercell tornado is the

A)gust front.
B)hook echo.
C)shelf cloud.
D)roll cloud.

Question 49

A circular cluster of strong thunderstorms is a ________.

Question 50

Doppler radar helps the meteorologist to

A)hear storm noises much more clearly.
B)infer the movement of air within a storm.
C)see through hills and mountains.
D)interrogate much larger sectors of the atmosphere than was possible with conventional radar.

Question 51

The mature stage of air-mass thunderstorms

A)is marked by an absence of significant downdrafts.
B)occurs before the anvil shape at the top of the cloud has formed.
C)sees the end of additional water vapor entering the cloud.
D)is marked by the heaviest precipitation.

Question 52

Describe the characteristics of these successive stages of air mass thunderstorm formation and dissipation.

Question 53

The cumulus stage of air-mass thunderstorm development

A)is marked by strong updrafts throughout the cloud.
B)is when much of the storm's precipitation occurs.
C)begins when unstable air begins to rise.
D)occurs before the Bergeron process starts.

Question 54

The only requirement for a thunderstorm is

A)sinking air.
B)still air.
C)rising air.
D)upper level convergence.

Question 55

Mesoscale convective complexes are self-sustaining because

A)wind shear is typically absent.
B)downdrafts from individual cells become warmer as the precipitation evaporates.
C)downdrafts from individual cells rise over the outflow boundary.
D)downdrafts from individual cells combine with surface winds to create updrafts and wind shear.

Question 56

This phenomenon

A)is a type of updraft associated with severe thunderstorms.
B)typically flows in only one direction.
C)causes little damage at the surface.
D)is a major potential hazard at airports.

Question 57

A Mesoscale Convective Complex (MCC)is

A)a small group of air mass thunderstorms.
B)usually a line of severe weather.
C)totally disorganized and random in nature.
D)a group of self-propagating thunderstorm cells that can last for hours.

Question 58

The three stages of the air mass thunderstorm are

A)cumulus, mature, dissipating.
B)cumulus, dissipating, mature.
C)initial, mature, degenerating.
D)initial, middle, dissipating.

Question 59

Which of these can be characteristics of severe thunderstorms?

A)wind speeds in excess of 58 mph
B)hailstones one inch or larger in diameter
C)tornadoes
D)all of these

Question 60

An outflow boundary is

A)the leading edge of cold air from a thunderstorm downdraft.
B)a favorable place for future severe storm development, especially if two intersect.
C)can be clearly seen on radar images.
D)all of these

Question 61

The glaciated part of a thunderstorm is usually found at

A)the top of the storm.
B)the middle of the storm.
C)the bottom of the storm.
D)throughout the entire storm.

Question 62

Mesoscale convective complexes

A)are a common cause of severe weather in Canada.
B)are typically linear.
C)are not able to propagate new cells.
D)require potential stability in the atmosphere.

Question 63

Describe the size,duration,potential destruction,and physical characteristics of the various types of thunderstorms and thunderstorm complexes.

Question 64

Mesoscale convective systems

A)are individual thunderstorms called supercells.
B)do not last more than 12 to 24 hours.
C)typically have low water-vapor content.
D)require wind shear and substantial uplift.

Question 65

Which of the following stages of thunderstorm development is characterized by the dominance of downdrafts and entrainment of the storm?

A)cumulus
B)mature
C)dissipating
D)none of these

Question 66

The principle hazard of microbursts to aircraft in the process of taking off or landing is

A)windblown sand and dust damaging jet engines.
B)sudden changes in lift and tailwinds.
C)Doppler radar.
D)lightning.

Question 67

For a cumulus cloud grows that taller over time but never develops a downdraft,

A)precipitation will not occur.
B)precipitation will be in the form of rain.
C)all lightning will be cloud-to-ground.
D)the thunder will have a weak, rumbling sound.

Question 68

In the United States,thunderstorms are most common in

A)central Florida.
B)Kansas.
C)Oklahoma.
D)Louisiana.

Question 69

Squall line thunderstorms

A)can have lengths of up to 100 kilometers.
B)are most common in late winter.
C)have downdrafts that create a gust front.
D)usually consist of five or fewer cells.

Question 70

The ability to detect mesocyclones using Doppler radar

A)reduces the risk of damage of stepped leaders.
B)allows meteorologists to predict where and when cumulonimbus clouds may form.
C)gives meteorologists the opportunity to change the direction of the rotation.
D)allows meteorologists to issue tornado warnings before tornados form.

Question 71

One of the most detrimental events that can occur to a developing thunderstorm is

A)entrainment.
B)lightning.
C)hail.
D)release of latent heat.

Question 72

Thunderstorms occur about how many times a day?

A)5,000
B)10,000
C)40,000
D)75,000

Question 73

Air mass thunderstorms

A)extinguish themselves through the formation of extensive downdrafts.
B)often last for several hours.
C)are associated with severe weather.
D)usually form at the borders of air masses.

Question 74

Explain how downdrafts create the strong precipitation within air mass thunderstorms,yet also cause the storm to die out.

Question 75

Globally,air mass thunderstorms are most common in the ________.

Question 76

In which stage of the air mass thunderstorm are there up- and down-drafts?

A)initial
B)middle
C)dissipating
D)mature

Question 77

Explain why strong vertical wind shear is a necessary ingredient of all intense thunderstorms.

Question 78

A thunderstorm becomes severe because

A)inflow equals outflow.
B)outflow equals inflow.
C)the updraft and downdraft become quasi-steady state.
D)entrainment enhances convection.

Question 79

Describe the Doppler effect and how it is applied with Doppler radar to study thunderstorms and severe storms.

Question 80

According to data from lightning detection networks,the average thunderstorm across the continental United States and Canada produces ________ lightning strikes.

A)36
B)100
C)200
D)280