Can you have lightning without thunder?

Answer 1

Never. Thunder and lightning always come together. But you'd never know it. You always see the lightning before you hear the thunder. That's because light travels super fast, at 186,000 miles (300,000km) a second! Sound is much slower, at only about 1/5 mile (0.3km) a second. So first you see lightning, then you hear the thunder.

Thunder is a result of Lightning. When hot air hits cold air it creates friction and that friction creates lightning. There is more to it than that, this is the quick version. Since light is the fastest speed you will hear the sound of thunder much later because sound is slower than light. Popular thinking will tell you that the time between lightning and thunder is the distance you are from the action. 1 second = 1 mile.

Answer 2

I have seen "lightening" all around, tonight in fact, and heard no thunder. But there were no bolts--it was bursts of lights in the clouds that lit up the sky. I have seen this other times as well on humid warm nights (in Western North Carolina). Later this evening, it did rain.

I found a reference to "heat lightning" on Wikipedia that indicates "Heat lightning is a misnomer for the faint flashes of lightning on the horizon or other clouds from distant thunderstorms that do not have accompanying sounds of thunder. Heat lightning was named because it often occurs on hot summer nights, and to distinguish it from lightning with accompanying thunder. Ordinary lightning results from the discharge of negative ions created from the friction of ice and water particles bumping into each other at the bottom of a cloud. Heat lightning can be an early warning sign that thunderstorms are approaching..."

"There are two possible reasons for the lack of thunder. In some cases, the thunderstorm may be too distant to hear the associated thunder from the lightning discharge. Thunder rarely travels more than 10 miles[citation needed]. Other cases can be explained by the refraction of sound by bodies of air with different densities. An observer may see nearby lightning, but the sound from the discharge is refracted over his head by a change in the temperature, and therefore the density, of the air around him. As a result, the lightning discharge seems to be silent. "Under optimum conditions the most intense thunderstorms can be seen at up to 100 miles (161 km) or more distant over flat terrain or water when the clouds are illuminated by large lightning discharges, though an upper limit of 30-50 (48-80 km) miles is more common due to topography, items on the horizon like trees and so on, the fact that local visibilities above 25 miles (40 km) are uncommon in most areas, and other low and mid level clouds. Variability of anvil height also contributes -- 45 000 feet (13 715 m) is very common in the mid latitudes for warm season thunderstorms but the range can be from 35 000 (10 665 m) to a current record of 78 000 feet (23 770 m). There is evidence that suggests some cases of heat lightning are, in fact, slow, diffuse discharges of electricity." http://en.wikipedia.org/wiki/Heat_lightning