heat lightning

noun

1. uncountable Lightning and/or thunder which the observer attributes to heat rather than a storm (e.g. because the storm/rain is too distant to be seen, or because there is no rain, as with dry lightning). Joel Brinkley, a schoolteacher, who was a child in the 1950s, recalled a similar feeling during this era: "It seems surreal now. Every summer, when I heard heat lightning over the city and the sky would light up, I was convinced it was all over. My whole childhood was built on the notion that the So
2. uncountable, in particular Visible lightning that occurs too far away for the resulting thunder to be audible by the observer. The typical range at which thunder can be heard is around 24 km [...] Often, people mistakenly call lightning whose thunder is too far away to be heard "heat lightning," suggesting that the lightning somehow owes its existence merely to the heat of the day and not to a thunderstorm. Nonsense. "Heat
3. uncommon, uncountable Thunder that is heard without lightning being seen by the observer; heat thunder. THE RAIN FINALLY CAME FROM THE DARK GREY SKIES, SOFT AND TEMPTING AT FIRST, WITH THE SOUND OF HEAT LIGHTNING HOVERING OVER THE SKYSCRAPERS! [image is of a city being rained on, no lightning visible]