I have always wondered about "heat lightning". What is this type of lightning and is it possible to be struck by it? Also, it is likely for "regular" lightning to strike someone who is talking on a cordless phone, working on a computer or taking a bath or shower during a storm?
Posted June 9, 2007
MIKE MOSS SAYS: Susan, Heat lightning is just an informal term that arose to describe "regular" lightning that is too distant to see the actual lightning channel, so that what is seen is just indirect light from the strike that is reflected off clouds or scattered by air and suspended particles. Often, since the storm producing the lightning is far away and low on the horizon, the reflected and scattered light takes on a reddish tint due to the fact that shorter wavelengths are preferentially scattered off tot he side as the light travels in your direction, leaving mainly the longer red, orange and yellow wavelenghts for you to see. In many cases, no thunder is heard from "heat lightning," again due to the large distance to the storm and to the fact that thunder is often inaudible for lightning strikes more than about 10 miles away.
As for being struck by heat lightning, the odds are very low so long as it remains too far away to see the lightning path and hear thunder. However, if the storm is moving in your direction and continues to produce lightning, it is of course possible to be struck. In addition, in rare instances a storm can produce a lightning bolt that originates high in the storm or high along it's side, and these strikes can reach the ground as much as ten miles away from the storm.
Finally, regarding applicanes indoors during a thunderstorm, the rule of thumb is that although the chances of being struck are small, you are in at least some danger if you are very near a device that is connected directly to a power source by way way of wiring or to the outside by way of metal plumbing, either of which could conduct a lighting surge inside. A cordless phone is generally safe (indoors and away from windows, that is), since it is separated from the base unit.