MONTGOMERY, Ala. (WSFA) - Prepare yourself, y’all. We’re about to tell you something about a highly used weather phrase that may come as a bit of a surprise. It’s likely a term you’ve used many times, but you’re probably not aware that the definition is not what it’s made out to be.
The term being referred to is heat lightning.
More often than not, folks use the term to describe the flashes of lightning that occur during the summer months while it’s dark outside. It doesn’t sound crazy at all.
Picture a super warm evening with high humidity and clouds in the distance. Chalking those flashes up to heat lightning makes perfect sense. It’s quite literally “hot” outside, and you don’t hear any thunder. So why not call it heat lightning?
Well, here comes the news you may not want to hear: the lightning flashes you’re seeing are not caused by heat and humidity at all. Rather, they are actually lightning strikes from an ongoing thunderstorm in the distance -- possibly way in the distance.
All lightning strikes originate from a thunderstorm. When you are far away from a storm, you just don’t see the actual lightning bolt hit the ground. Your view of a distant thunderstorm is only of the top layers of it because of the curvature of the earth (see diagram above).
You simply can’t see the bottom of the storm, nor the ground when storms are distant enough. Not only that, but when you are more than 10 miles or so away from a storm, you cannot hear any thunder.
So combining the lack of seeing the bolt hit the ground and the lack of thunder, it makes any nighttime lightning flashes appears as though they are simply originating out nowhere in the far distance.
Alas, they are originating from actual thunderstorms that are just too far away for you to see!