Very large thunderstorms can produce phenomena called sprites. Very intense. A thunderstorm must produce a special kind of flash, and it is quite rare. Maybe one flash out of a thousand will produce a sprite.
These flashes should remove a lot of electrons from the thundercloud. It takes a long, slow current to form a sprite, and such currents can form in large thunderstorm systems up to 100 kilometers across.
The elusiveness of these powerful red flashes has given them their ethereal name, taken from Shakespeare's A Midsummer Night's Dream. But as the prices of powerful cameras fall, sprites are caught on them more and more often.
Even an ordinary camera with good night vision can take a poor quality picture. Meteor watchers also often collect data on sprites.