What is sheet lightning?

What is sheet lightning?

Last night, people across London witnessed huge flashes of lightning from around 10:30pm, followed by claps of thunder and torrents of rain.

The warning says: ‘Thunderstorms, with locally torrential downpours will continue to move north across England and Wales in the early hours of this morning.

‘Although the thunderstorms will tend to ease from the south later in the night, further, possibly severe storms may break out again this afternoon, probably focused over parts of northeast Wales, central and northern England.
The type of lightning seen last night – which lit up the whole sky – is known as sheet lightning. But what does that mean?

Sheet lightning, also known as intra-cloud lightning, refers to lightning within a cloud that lights up as a ‘sheet’ of luminosity during the flash.
The lightning itself can’t be seen by a spectator, so it appears as a flash, or sheet of light.

Click here to watch video
http://video.metro.co.uk/video/met/2017/07/19/1763780663285926092/640x360_MP4_1763780663285926092.mp4

It can also be too far away to make out individual flashes.
This lightning inside a storm cloud jumps between different charge regions within it, with all or parts of it hidden.