Why is there never thunders during winters? Shoudnt the cold air be even more conductive?
Cold air is less energetic. The process by which lightning is generated is not yet fully understood, but it does seem to require a lot of energy. For one thing, lightning only seems to come from cumulonymbus clouds, those big, tall clouds with the "anvil-shaped" tops that you allways see in association with thunderstorms. The formation of these clouds requires strong updrafts, which are very seldom found in cold air. And the storm itself is certainly a very energetic process.
There is also some evidence that te alternate freezing and thawing of the airborn H2o plays a role in charging the cloud.
I have heard that lightning can come from a snowstorm, it's just a very rare event.
just an aside, but here in the uk we had snow storms last week which had lightning in them.
Live in Canada, have experianced both...
EDIT yes it is a rare thing, the cold apparently 'dampens' things, cold air holds less moisture...the reasoning behind the "It Never snows when it is really reeally cold" (falacy) cause it can, but it is 'more rare', produces some really nice snow though, "Champagne" Snow, crosscountry skied in it, beauty!
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