Is Lightning AC or DC?

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Neither. Since it is a static charge, I wouldn't lump it in with either AC or DC which normally are used to describe a sustained current or waveform that travels in a complete circuit.

DC is left if anyone wants to pick that answer :)

Steve
 
Initially It is DC with an extremely fast rise time which gives it a high frequency AC component at the initial strike. Once the arc is established it contains all frequencies in the RF spectrum which makes it AC.
 
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dereckbc said:
Initially It is DC with an extremely fast rise time which gives it a high frequency AC component at the initial strike. Once the arc is established it contains all frequencies in the RF spectrum which makes it AC.
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The streamers are unipolar but as soon as the strike established, the ionized air becomes plasmatic and conductive it is pure AC as BOTH polarity charges flow in opposing direction simultaneously.
 
weressl said:
The streamers are unipolar but as soon as the strike established, the ionized air becomes plasmatic and conductive it is pure AC as BOTH polarity charges flow in opposing direction simultaneously.
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Thought that is what I said :grin:
 
weressl said:
The streamers are unipolar but as soon as the strike established, the ionized air becomes plasmatic and conductive it is pure AC as BOTH polarity charges flow in opposing direction simultaneously.
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My NWS training does not agree with you. No matter, over the years this has come to rival beating a dead horse.
 
dereckbc said:
Thought that is what I said :grin:
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I am sure that is what you meant to say.

Unless there is a current flow, which there isn't until the strike established, one can not speak either AC nor DC. I am not aware that they were able to detect DC flow, even if for a very short while, at the front end of the strike. If there is a DC 'component' there, like at regular arc flash, I have not heard it identified that way.

Ther is SOOOOOO little known about lightning that everything is still open. So we both can be wrong. One of the hypotheses currently is that the charges accumulate from cosmic particle charges and not necessarily from the water particles rising due to heat evaporation. So even though the charges are accumulated in the clouds formed by rising water molecules but the main charges are 'extraterrestial'. The clouds act like interceptors, screens. One of the evidence pointing to this are the mega-lightning events that do not occur between clouds and ground, but seem to be projecting toward out into the space and they are 20+miles long. Fascinating.....:cool:
 
I couldn't say for sure because I have never been able to get that pesky bolt through the opening in my ammeter:grin:


If I had to guess I would go with neither and both. Initially a DC static charge and once the bolt strikes anything goes.
 
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