Question: How is heat suddenly generated to the extent of 50,000 Fahrenheit during lightning?

Ceri Brenner answered on 14 Jun 2011:

hi,
that’s a good question because lots of people are fascinated at how lightning forms.
Here’s how i understand it:
during a storm, the clouds become charged up (they accumulate either a positive or negative charge as opposed to being electrically neutral), to the extent where they reach their full capacity for storing charge and so they need to discharge that electrical energy. a common way that charged up things can discharge themselves is by grounding the electric current (the current needs to pass to the ground and restore the charge neutrality). it’s the same thing (in principle) as when you get a static shock from a car door for example-the stored up charge in the car jumps from the car to your finger to ground itself.

so lightning is basically when this huge store of electrical energy is discharged through the air to ground. the electricity needs to form a pathway from the clouds to the ground through which current can travel, so you need a state of matter in which free electrons can move in a gas, so you need a plasma! The electrical energy passes from the clouds to the ground by instantaneously producing a plasma state. The huge current crosses the potential difference between the clouds and the ground in a very short space of time and the action of all these electrons zooming to the ground causes the air in which they travel to heat up very rapidly (to the temperature that you mentioned). Think about how hot a wire can get if you send a strong current through it. The light comes as the electrons and ions recombine and photons (light particles) are given off. The thunder comes as the action of a strong current pushing it’s way down to the ground causes a shock wave to pass through the air surrounding the lightning pulse.