Intracloud Lightning, Sheet Lightning, Anvil Crawlers

Intracloud lightning is the most common type of lightning which occurs completely inside one cumulonimbus cloud, and is commonly called sheet lightning or an anvil crawler. Discharges of electricity in anvil crawlers travel up the sides of the cumulonimbus cloud branching out at the anvil top. Sheet lightning can be seen when lightning is close to the horizon. You cannot see individual lightning strikes but the whole cloud will be seen to 'light up'.