Lightning in winter

[Angie Norris]

Ok, dumb question time...other than the fact there are relatively fewer thunderstorms in winter, why is there relatively little lightning in the mid latitudes in winter? ( I've lost a few pages of notes, and that answer is among the lost pages)Thanks bunches in advance, and good luck to everyone on their finals!!!!!!

 

[John Olexa]

http://www.ccmr.cornell.edu/education/ask/index.html?quid=623

 

[rdale]

other than the fact there are relatively fewer thunderstorms in winter

Lightning can only come from a thunderstorm - so no storm by default means less lightning.

So think about the cause of thunderstorms. You need sufficient lift, moisture and instability. Lift in winter? Sure. Moisture? Dew points are frequently in the teens and 20's, and there ain't much juice in numbers that low. Instability? Surface temps in the 30's won't give you much CAPE...

 

[Steven Williams]

I would also add to the answer that ocean areas usually only produce only weak lightning activity at any time of the year. And of course the land areas are stable in winter.

 

[Gene Moore]

Ok, dumb question time...other than the fact there are relatively fewer thunderstorms in winter, why is there relatively little lightning in the mid latitudes in winter? ( I've lost a few pages of notes, and that answer is among the lost pages)Thanks bunches in advance, and good luck to everyone on their finals!!!!!!

Lightning is tied to cloud height vs temperature. Working from memory here I believe the magic number is the -28C isotherm (LOL, if that's wrong I'm sure the correction will be forthcoming

).

Anyway, to get lightning (without going into the specifics of the cloud physics) you need an updraft that reaches that temperature to get proper separation of charges. This means a cloud in vertical height of roughly 20,000 to 25,000 feet in the cold season. Of course this can change drastically with latitude. Let's look at the current central OK situation. Freezing rain thunderstorms have been reported there over the last 24 hours. Looking at the sounding we have -28C just above 400 Mb or about 25,000 feet. Current radar tops as I type this message are 25,000 to 30,000 feet. That should be high enough for lightning in these particular cells. Taking this a step further, when it's very cold aloft we can get lighting with much lower cloud tops. In a cold core winter low (aloft) temperatures at 500 Mb or 18,000 feet can fall below -30C. It these situations the lightning can result from clouds under 20,000 feet. Certainly not classic thunderstorms as we are used to on the plains, yet there is still lighting occasionally in these situations. One common area is the lake effect snow coming off Lake Erie with streamers into New York state. Observations of lightning with these lower top lake effect systems do show up on the aviation hourlies. There might even be some lake effect snow - lightning pictures, although the snow would probably be so heavy the bolt wouldn't show up...anyone tried this?

Gene Moore