Lightning Part 1

Question 1

What cloud is a thunderstorm?

Answer 1

Cumulonimbus

Question 2

What electrical charge does the Earth’s surface carry on a clear day?

Answer 2

Negative

Question 3

What is thunder the consequence of?

Answer 3

Lightning

Question 4

Are sound waves slower or faster than light waves?

Answer 4

Slower

Question 5

Will thunder be heard before or after lightning?

Answer 5

After

Question 6

What is the electrosphere?

Answer 6

The region in the atmosphere where the electrical resistivity is constant (~50km)

Question 7

What is the fair-weather electric current?

Answer 7

The small current between the electrosphere (positive) and the Earth (negative). ~1500 amps

Question 8

What maintains the charge in our capacitor (The Earth)?

Answer 8

Thunderstorms and lightning

-thunderstorm system acts by providing a negative current to the ground

Question 9

How quickly would the capacitor discharge if it was left alone?

Answer 9

5.5 minutes

Question 10

How is a classical thundercloud model described?

Answer 10

It is described as a positive electric dipole with a positively charged region above a negatively charged region

Question 11

How is a thundercloud structured?

Answer 11

There are three centers (P, N, PI)

• Upper positive region, P, occupies the top half of the cloud
• The negatively charged region, N, is located in the middle of the cloud
• The lowest region, PI, is a weak, positive charged center at the cloud base
• The N and the X regions have approximately the same charge, creating the positive dipole

Question 12

What is a positive dipole?

Answer 12

The separation of the positive and negative charges found in any electromagnetic system

Question 13

What is the convective theory of how thunderclouds get charged?

Answer 13

It proposes that free ions in the atmosphere are captured by cloud droplets and then are moved by the convective currents in the cloud to produce the charged regions

Question 14

What is the gravitational theory of how thunderclouds get charged?

Answer 14

It assumes that negatively charged particles are heavier and are separated from lighter positively charged particles by gravitational settling.

Question 15

What is the screening layer?

Answer 15

Negative charge carries in the atmosphere are attracted to the cloud

Question 16

What is the inductive theory of the gravitational theory?

Answer 16

It assumes that charge is exchanged between colliding particles polarized by the fair-weather electric field.

Question 17

What is the non-inductive theory?

Answer 17

When warm and cold ice particles come in contact, the positive ions flow from the warmer to the colder particles faster than from the cold particles to the warm particle. Thus, the colder particles receive a net positive charge.

Question 18

What are the four types of lightning?

Answer 18

1) intracloud
2) cloud-to-air
3) cloud-to-cloud
4) cloud-to-ground

Question 19

What are the three stages of the lightning flash?

Answer 19

• The stepped leader
• The return stroke
• The dart leader

Question 20

What is the stepped leader?

Answer 20

A small packet of negative charge that descends from the cloud to the ground along the path of least resistance

Question 21

What is the return stroke?

Answer 21

The next step of a lightning flash that rapidly moves as a wave upwards into the cloud following the ionized trail of the stepped leader, stripping the electrons from its path. It is triggered when the downward-moving leader connects with a surface corona discharge and a continuous path between the cloud and the ground is established.

Question 22

What is the dart leader?

Answer 22

Occurs if enough charge in the cloud is collected after the return stroke. It triggers a second return stroke

Question 23

What is the positive corona discharge?

Answer 23

A region of positive charge created as the stepped leader approaches the ground and the electrons on the surface retreat from the leader.