Cloud Electrification and Lightning Questions and Answers

Q: Global lightning activity is estimated at approximately how many flashes per second?

Correct answer: 45 flashes per secondSatellite observation gives a global average near 45 flashes a second, or some 1.4 billion a year, with the great majority over land in the tropics. The figure varies by a factor of two through the day and the year as the global thunderstorm activity varies, and it is that variation which the fair weather field over the ocean follows.

Q: Three of the following are regions of high lightning activity. Which is the odd one out?

Correct answer: the central Pacific oceanThe central Pacific has among the lowest flash rates on earth, for exactly the reason given by the previous item - weak convection over water whose surface temperature barely varies. The other three are among the world’s lightning maxima: the Congo basin, which holds the global record, northern Argentina and Paraguay, and central Florida, the most active region of the United States.

Q: Match each transient luminous event with where it occurs.List IA. SpriteB. Blue jetC. ElveD. Gigantic jetList II1. a rapidly expanding ring in the lower ionosphere2. mesosphere above a thunderstorm3. from cloud top all the way to the ionosphere4. upward from the cloud top into the stratosphere

Correct answer: A-2, B-4, C-1, D-3The four transient luminous events occupy different altitudes. A sprite is a red discharge in the mesosphere, 50 to 90 km up, triggered by a large charge transfer below. A blue jet shoots upward from the cloud top into the stratosphere. An elve is a rapidly expanding ring in the lower ionosphere, produced by the electromagnetic pulse of the flash. A gigantic jet bridges the whole gap from cloud top to ionosphere.

Q: State whether the following is true or false.Sprites are usually triggered by positive cloud to ground flashes.

Correct answer: TrueSprites are almost always triggered by positive cloud-to-ground flashes, which transfer far more charge from a greater height than typical negative flashes and so produce the large charge moment change needed to drive breakdown in the mesosphere. They occur most often above the trailing stratiform region of a mesoscale convective system, where such positive flashes are concentrated.

Q: Consider the following statements about lightning detection.1. Time of arrival at several sensors locates a stroke.2. The radio pulse travels far enough for wide sensor spacing.3. Detection requires an observer to see the flash.

Correct answer: 1 and 2 onlyStatements 1 and 2 describe how a modern network works: the radio pulse from a return stroke propagates for hundreds of kilometres, so sensors can be widely spaced, and comparing the arrival times at several of them locates the stroke by multilateration. Statement 3 is wrong - detection is entirely electromagnetic, and the networks work at night, in daylight, through cloud and over the ocean where no observer is present.

41.

Global lightning activity is estimated at approximately how many flashes per second?

A.45 flashes per second
B.4 flashes per second
C.450 flashes per second
D.4500 flashes per second

Answer: A

Correct answer: 45 flashes per second

Satellite observation gives a global average near 45 flashes a second, or some 1.4 billion a year, with the great majority over land in the tropics. The figure varies by a factor of two through the day and the year as the global thunderstorm activity varies, and it is that variation which the fair weather field over the ocean follows.

Discuss in Forum

42.

Assertion (A): Lightning is far more frequent over land than over the ocean.
Reason (R): Land heats rapidly and supports the vigorous updraughts that charging requires.

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

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

Both are true and the reason gives the mechanism. Land has a low heat capacity and warms quickly in the sun, driving strong surface heating and the vigorous updraughts that carry supercooled water above the freezing level. The sea warms slowly and its surface temperature varies little through the day, so oceanic convection is generally weaker and the lightning rate lower by a factor of ten.

Discuss in Forum

43.

Three of the following are regions of high lightning activity. Which is the odd one out?

A.central Florida in summer
B.northern Argentina and Paraguay
C.the central Pacific ocean
D.the Congo basin in central Africa

Answer: C

Correct answer: the central Pacific ocean

The central Pacific has among the lowest flash rates on earth, for exactly the reason given by the previous item - weak convection over water whose surface temperature barely varies. The other three are among the world’s lightning maxima: the Congo basin, which holds the global record, northern Argentina and Paraguay, and central Florida, the most active region of the United States.

Discuss in Forum

44.

Sprites are

A.small bright discharges deep within the cloud
B.a form of ball lightning close to the ground
C.the upward streamers that precede attachment
D.large faint red discharges above active thunderstorms

Answer: D

They occur in the mesosphere at fifty to ninety kilometres and last only milliseconds. They are usually triggered by large positive cloud to ground flashes. Their existence was only confirmed in the late twentieth century.

Discuss in Forum

45.

Match each transient luminous event with where it occurs.
List I
A. Sprite
B. Blue jet
C. Elve
D. Gigantic jet
List II
1. a rapidly expanding ring in the lower ionosphere
2. mesosphere above a thunderstorm
3. from cloud top all the way to the ionosphere
4. upward from the cloud top into the stratosphere

A.A-2, B-4, C-1, D-3
B.A-4, B-2, C-1, D-3
C.A-2, B-4, C-3, D-1
D.A-3, B-1, C-4, D-2

Answer: A

Correct answer: A-2, B-4, C-1, D-3

The four transient luminous events occupy different altitudes. A sprite is a red discharge in the mesosphere, 50 to 90 km up, triggered by a large charge transfer below. A blue jet shoots upward from the cloud top into the stratosphere. An elve is a rapidly expanding ring in the lower ionosphere, produced by the electromagnetic pulse of the flash. A gigantic jet bridges the whole gap from cloud top to ionosphere.

Discuss in Forum

46.

State whether the following is true or false.
Sprites are usually triggered by positive cloud to ground flashes.

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

Answer: B

Correct answer: True

Sprites are almost always triggered by positive cloud-to-ground flashes, which transfer far more charge from a greater height than typical negative flashes and so produce the large charge moment change needed to drive breakdown in the mesosphere. They occur most often above the trailing stratiform region of a mesoscale convective system, where such positive flashes are concentrated.

Discuss in Forum

47.

A lightning detection network locates strokes by

A.measuring the thunder heard at the nearest station
B.detecting the charge left within the cloud immediately afterwards
C.timing the arrival of the radio pulse at several stations
D.photographing the flash from a single ground station

Answer: C

Time of arrival and direction finding at multiple sensors fix the position by triangulation. The electromagnetic pulse propagates for hundreds of kilometres, which gives such networks a wide reach. Sensor spacing of hundreds of kilometres is workable.

Discuss in Forum

48.

Consider the following statements about lightning detection.
1. Time of arrival at several sensors locates a stroke.
2. The radio pulse travels far enough for wide sensor spacing.
3. Detection requires an observer to see the flash.

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

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 describe how a modern network works: the radio pulse from a return stroke propagates for hundreds of kilometres, so sensors can be widely spaced, and comparing the arrival times at several of them locates the stroke by multilateration. Statement 3 is wrong - detection is entirely electromagnetic, and the networks work at night, in daylight, through cloud and over the ocean where no observer is present.

Discuss in Forum

49.

A lightning rod protects a structure principally by

A.providing a preferred low resistance path to earth
B.repelling the approaching leader electrostatically
C.preventing charge from accumulating in the cloud
D.absorbing the entire energy of the stroke

Answer: A

It intercepts the discharge and conducts the current safely into the ground. The structure is protected because the current bypasses it rather than because the strike is prevented. The rod controls the path rather than the occurrence.

Discuss in Forum

50.

State whether the following is true or false.
A lightning rod prevents lightning from striking a building.

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

Answer: B

It offers a preferred path once a strike occurs but does not stop it happening. The protection lies in controlling where the current flows, not in avoiding the strike altogether. This is the most commonly misunderstood point about protection.

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