Heat lightning

[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".

Usually, the troposphere will reflect the light, and leave out the sound - in these cases some fraction of the light emanating from distant thunderstorms (whose distant clouds may be so low to the horizon as to be essentially invisible) is scattered by the upper atmosphere and thus visible to remote observers.

Under optimum conditions, the most intense thunderstorms can be seen at up to 100 miles (160 km) over flat terrain or water when the clouds are illuminated by large lightning discharges.

The height of the anvil (the large, plume-like top of a thunderhead) also contributes—45,000 feet (14,000 m) is very common in the mid latitudes for warm-season thunderstorms, but the anvil height can range from 35,000 feet (11,000 m) to a current record of 78,000 ft (24,000 m).