Which one is correct statement regarding lightning?

[songoku]

Homework Statement

Please see below

Relevant Equations

None

My answer is (B) but the correct answer is (D). I don't understand why there is induction between clouds and ground. I thought there will only be separation of charges in ground (polarization) due to large negative charges in the clouds causing the ground below the clouds will be positively charge but overall charge of the ground will still be neutral so there is no induction process between clouds and ground.

Why (D) is the correct answer? Thanks

 

[.Scott]

I would interpret the diagram this way:
Both clouds are discharging electrons (negative charge) to the ground. This is evidence that there had previously been a charge induced between the clouds and the ground. Polarization of the charge in the cloud to the left also allows the cloud on the right to discharge into the cloud on the left.

 

[songoku]

I would interpret the diagram this way:
Both clouds are discharging electrons (negative charge) to the ground. This is evidence that there had previously been a charge induced between the clouds and the ground. Polarization of the charge in the cloud to the left also allows the cloud on the right to discharge into the cloud on the left.

If that is the case, there is discharging between the clouds so can I say there is induction between clouds?

Thanks

 

[haruspex]

separation of charges in ground (polarization) due to large negative charges in the clouds causing the ground below the clouds will be positively charge

Also known as induction.

 

[.Scott]

I believe @haruspex nailed it.
A charge induce on the ground by a cloud is called induction. It's the term used in that situation.

 

[songoku]

Also known as induction.

For this case, is this also called induction?

 

[Gavran]

I don't understand why there is induction between clouds and ground. I thought there will only be separation of charges in ground (polarization) due to large negative charges in the clouds causing the ground below the clouds will be positively charge but overall charge of the ground will still be neutral so there is no induction process between clouds and ground.

Why (D) is the correct answer? Thanks

When we speak about electrostatic induction, we speak in the context of charges of regions of the object, not in the context of charges of the overall object. The object can be neutral, but its charges cannot be evenly distributed. The polarization in this case is caused by what you have described in the original post.

 

[haruspex]

View attachment 367714
For this case, is this also called induction?

Yes: https://en.wikipedia.org/wiki/Electrostatic_induction#Induction_in_dielectric_objects

 

[songoku]

Thank you very much .Scott, haruspex, Gavran

 

[kuruman]

I think that the drawing would be more accurately drawn if the lightning hit the tree instead of the ground on its left. As negative charges build up at the base of storm clouds, they induce a swell of positive charges, or "streamers," to rise from the ground. Taller, more conductive objects like trees are prone to developing these upward streamers as the equipotential planes, normally parallel to the Earth and equidistant, are pushed closer together by the presence of the tree thus creating a locally stronger electric field. When a downward leader from the cloud meets one of these upward streamers, a lightning strike occurs, and the tree becomes part of the electrical circuit to the ground.