What Causes Cloud-to-Ground Lightning Instead of Intra-Cloud Discharge?

[Somnolence]

From what I understand lightning works like a simple capacitor.

The convection brings up moist air that by collision with already condensed gas molecules, causes charge separation within the cloud. The bottom part of the cloud becomes negative while the top part becomes positive. The lower part of the cloud establishes a strong electric field between the upper and lower parts of the cloud as well as between the cloud and ground. Just like a capacitor. Turbulent air within the cloud makes it hard for charge from the bottom of the cloud to move up to the top of the cloud to equalize the charges.

Now to my question:
How can it be possible for a cloud to discharge to the ground rather than to discharge towards its upper sections witch I assume is by far much closer in space than the ground below the cloud.

 

[davenn]

Hi Somnolence
welcome to PF

because the charge separation between the cloud and ground can be larger than that between areas within the cloud. Also the distances involved are often much less between the base regions of the cloud and the ground
than to the upper regions of the cloud

eg. the cloud base may only be around 1,000 metres above the ground, often much less.
Whereas the distances from the base area to the upper cloud areas can easily be 8,000 - 15,000 metres

So its much easier to discharge across the shorter distance

cheers
Dave

 

[cyklop]

In addition, there are frequent cloud-to-cloud discharges. There is a video of this happening as taken from the International Space Station floating aroundon YouTube. Try using the search terms "lightning space station".

 

[davenn]

In addition, there are frequent cloud-to-cloud discharges. ...

yes, but that wasn't the question

I photo and video many CC discharges along with the CG's


Dave

 

[Somnolence]

Thanks for the replies! :D