Heat lightning

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Heat lightning (not to be confused with dry thunderstorms, which are also often called dry lightning) is a misnomer^[1] used for the faint flashes of lightning on the horizon or other clouds from distant thunderstorms that do not appear to have accompanying sounds of thunder.

The actual phenomenon that is sometimes called heat lightning is simply cloud-to-ground lightning that occurs very far away, with thunder that dissipates before it reaches the observer.^[2] At night, it is possible to see the flashes of lightning from very far distances, up to 100 miles (160 km), but the sound does not carry that far.^[3] In the United States, lightning is especially common in Florida, which is considered the deadliest state for lightning strikes in the country.^[4] This is due to high moisture content in the lower atmosphere and high surface temperature, which produces strong sea breezes along the Florida coast.^[5] As a result, heat lightning is often seen over the water at night, the remnants of storms that formed during the day along a sea breeze front coming in from the opposite coast.

Heat lightning is not to be confused with electrically induced luminosity actually generated at mesospheric altitudes above thunderstorm systems (and likewise visible at exceedingly great ranges), a phenomenon known as "sprites".