Weather Myths and Realities: Heat Lightning
"Rayo de Zeus" by Christian Frausto Bernal, licensed through Creative Commons
The following post is an example of a completed “Weather Myths and Realities” blog post.
People often refer to late summer evening lightning storms as “just heat lightning.” The impression is that there is no danger from this lightning. They think that because there is no accompanying sound of thunder, the lightning is not actually striking the ground. I have even heard this lightning explained as “just light in the clouds” not electric discharges.
The reality is, heat lightning does not exist. “Heat” lightning is regular lightning which occurs too far away for the thunder to be heard. Sound and light travel at different speeds, so the light can travel further, and the sound eventually dissipates to a point where it cannot be heard. Since it’s so far away, there is rarely any direct danger from the lightning for those viewing it, but it does indicate that a storm is in the area and could move in quickly. All lightning is electrical discharge within clouds or between the clouds and the ground. Though the “heat” lightning does not pose much danger to the person calling it such, it is dangerous to those experiencing it within the sound of the thunder.
Many people probably refer to heat lightning because they’ve never fully grasped the differences in the speed of sound and light. Since it poses no immediate danger, they feel they can stay outside doing whatever activity they are participating in at the time. Thunder and lightning are so closely related that people think they can’t have one without the other. Therefore, if there is no thunder heard, the lightning must be something other than what we normally experience.
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