sheet lightning 
noun [mass noun]
Lightning with its brightness diffused by reflection within clouds.Heat lightning is like sheet lightning, but is so far away that you cannot hear the thunder....
- The mixture of warm air and moisture creates thunderstorms at altitude - maybe 3,000 metres - bringing thunder and sheet lightning and heavy downpours from France, often at night.
- Like sheet lightning, these flashes are created by lightning bolts, but are in thunderstorms more than 10 miles away.
- photoengraver
- photoengraving
- photoenvironment
- photoenzymatic
- photoenzymatically
- photoenzyme
- photoequilibrium
- photoessay
- photo-etch
- photo-etched
- photo-etcher
- photo-etching
- photoexcitation
- photoexcite
- photoexcited
- photofabrication
- photo-filigrane
- photo finish
- photofinisher
- photofinishing
- photofission
- photofit
- photoflash
- photoflood
- photofluorogram