Cloud Electrification and Lightning Questions and Answers

Q: Consider the following statements about the reversal temperature.1. It marks where the sign of graupel charging changes.2. Its value depends on the liquid water content present.3. It is a single fixed temperature in all conditions.

Correct answer: 1 and 2 onlyStatements 1 and 2 are correct. Statement 3 is the simplification the second corrects: the reversal is not a single temperature but a boundary in temperature and liquid water content together, so a storm with a richer supply of supercooled water reverses at a colder temperature and places its negative centre higher. Quoting minus 15 degrees is a useful approximation rather than a physical constant.

Q: State whether the following is true or false.Rocket triggered lightning has been an important tool in measuring return stroke currents directly.

Correct answer: TrueFiring a small rocket trailing a grounded wire into a charged cloud triggers a flash at a known place and a known instant, so the current can be measured directly at the base of the channel and the electromagnetic fields recorded at known distances. It has supplied most of what is known quantitatively about return stroke currents, and it is how lightning protection standards have been validated.

Q: The stepped leader advances in steps of roughly

Correct answer: fifty metres at a timeThe stepped leader advances in luminous steps of roughly 50 metres, each lasting about a microsecond, with pauses of tens of microseconds between them - giving an average descent speed of some 200 km per second, far slower than the return stroke that follows. The stepping is what makes the leader visible on high speed film and gives the flash its name.

91.

Consider the following statements about the reversal temperature.
1. It marks where the sign of graupel charging changes.
2. Its value depends on the liquid water content present.
3. It is a single fixed temperature in all conditions.

A.1 only
B.All of them
C.1 and 2 only
D.3 only

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 are correct. Statement 3 is the simplification the second corrects: the reversal is not a single temperature but a boundary in temperature and liquid water content together, so a storm with a richer supply of supercooled water reverses at a colder temperature and places its negative centre higher. Quoting minus 15 degrees is a useful approximation rather than a physical constant.

Discuss in Forum

92.

Lightning nitrogen oxide production matters chiefly in

A.the boundary layer over large cities
B.the stratosphere above the ozone layer itself
C.the deep ocean far from any land
D.the upper troposphere where other sources are scarce

Answer: D

Correct answer: the upper troposphere where other sources are scarce

Lightning produces nitrogen oxides directly in the upper troposphere, where surface sources such as traffic and industry barely reach and where the resulting ozone production has a disproportionate effect on the radiative balance. It is a modest fraction of the global nitrogen oxide budget but the dominant source at that altitude, which is why it matters to atmospheric chemistry out of proportion to its size.

Discuss in Forum

93.

Cloud to ground flashes lower negative charge to the ground in the majority of cases, which means the ground receives

A.negative charge from the cloud
B.positive charge from the cloud
C.no net charge at all
D.charge of alternating sign each stroke

Answer: A

The main negative centre is the usual source of cloud to ground flashes. This transport of negative charge downward is what maintains the global circuit against fair weather conduction. The Earth carries a net negative surface charge.

Discuss in Forum

94.

Assertion (A): Thunderstorms maintain the negative charge of the Earth's surface.
Reason (R): The majority of cloud to ground flashes transfer negative charge downward.

A.A is false but R is true
B.Both A and R are true, and R is the correct explanation of A
C.Both A and R are true, but R is not the correct explanation of A
D.A is true but R is false

Answer: B

Both are true and the reason gives the mechanism, and point discharge currents contribute as well. The fair weather conduction current continuously opposes this transport. The two must balance in the long term average.

Discuss in Forum

95.

Three of the following are components of the global electric circuit. Which is the odd one out?

A.fair weather conduction currents
B.the conducting ionosphere
C.the radar bright band
D.thunderstorm generators

Answer: C

The bright band is a precipitation phenomenon with no electrical role. The other three are the recognised elements of the global circuit. The circuit is closed through the conducting ionosphere. The bright band belongs to precipitation physics.

Discuss in Forum

96.

Rocket triggered lightning is used to

A.prevent lightning from striking a protected facility
B.measure the fair weather field at the surface
C.generate electrical power directly from storms
D.study flash physics under controlled conditions

Answer: D

A small rocket trailing a grounded wire initiates a discharge at a known place and time. The technique has provided much of what is known about return stroke currents. Instrumented towers provide the other main source.

Discuss in Forum

97.

State whether the following is true or false.
Rocket triggered lightning has been an important tool in measuring return stroke currents directly.

A.True
B.False
C.True only at large scales
D.False only at small scales

Answer: A

Correct answer: True

Firing a small rocket trailing a grounded wire into a charged cloud triggers a flash at a known place and a known instant, so the current can be measured directly at the base of the channel and the electromagnetic fields recorded at known distances. It has supplied most of what is known quantitatively about return stroke currents, and it is how lightning protection standards have been validated.

Discuss in Forum

98.

The stepped leader advances in steps of roughly

A.one metre at a time
B.fifty metres at a time
C.five kilometres at a time
D.five millimetres at a time

Answer: B

Correct answer: fifty metres at a time

The stepped leader advances in luminous steps of roughly 50 metres, each lasting about a microsecond, with pauses of tens of microseconds between them - giving an average descent speed of some 200 km per second, far slower than the return stroke that follows. The stepping is what makes the leader visible on high speed film and gives the flash its name.

Discuss in Forum

99.

Assertion (A): Lightning channels are conspicuously branched.
Reason (R): The stepped leader explores several paths and only one completes the connection to ground.

A.A is true but R is false
B.A is false but R is true
C.Both A and R are true, and R is the correct explanation of A
D.Both A and R are true, but R is not the correct explanation of A

Answer: C

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the cause. The descending leader repeatedly divides, exploring several routes downward, and only one branch reaches the ground and carries the return stroke. The others are left behind as the fainter side branches of the visible flash. Because they were formed by a descending leader, they point downward - which is how the direction of the leader can be read from a photograph.

Discuss in Forum

100.

The direction in which the branches of a flash point indicates

A.the direction of the prevailing wind at the time
B.the polarity of the charge that was transferred
C.the distance from the channel to the observer
D.the direction in which the leader was travelling

Answer: D

Correct answer: the direction in which the leader was travelling

Branches point away from the direction of leader propagation, since each was a path the leader explored and abandoned as it advanced. Downward-pointing branches therefore indicate a downward leader, as in an ordinary cloud-to-ground flash, and upward-pointing branches indicate a flash initiated upward from a tall structure. It is one of the few things about a flash that can be read directly from a photograph.

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Cloud Electrification and Lightning Questions and Answers || Cloud Electrification and Lightning MCQ Questions and Answers || Cloud Electrification and Lightning GK Questions and Answers || Cloud Electrification and Lightning GK MCQ Questions || Cloud Electrification and Lightning Multiple Choice Questions and Answers || Cloud Electrification and Lightning GK || GK on Cloud Electrification and Lightning || Cloud Physics Questions and Answers || Cloud Physics MCQ Questions and Answers || Cloud Physics GK Questions and Answers || GK on Cloud Physics

Cloud Electrification and Lightning Questions and Answers

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications