Images of what has been described as a "rare natural phenomenon" have been captured on Sandburn beach outside Sunderland.
These clouds are only visible when tiny crystals on the edge of space are illuminated by sunlight while the lower layers of the atmosphere are in the Earth's shadow.
The clouds are described as "noctilucent", meaning 'night shining' in Latin.
Photographer Mat Robinson said: "They happen in the summer months between May and August when the sun doesn't set too far below the horizon.
"There weren't any recordings of them before 1885, so they are a relatively new phenomenon and could be linked to global warming."