heat lightning
noun
- noun 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).
- noun (in particular) Visible lightning that occurs too far away for the resulting thunder to be audible by the observer.
- noun (less commonly) Thunder that is heard without lightning being seen by the observer; heat thunder.
Etymology
So called because it is common on hot summer nights and is sometimes popularly thought to be caused by heat rather storms.
Sources: Wiktionary — from the Wiktionary entry “heat lightning”, CC BY-SA 4.0. Details