How long did naval illumination flares burn, how high were they dropped, and how did they affect defenders?
Short answerDropped near cloud height, they burned for minutes, silhouetted ships and made the shift between bright and dark areas especially disruptive to night vision.
NotesFlares were released around cloud height, several thousand feet above the target area. They stayed aloft for minutes and produced an intense light comparable to daylight over the illuminated zone. Ships stood out against that background while nearby darkness appeared even deeper. For anti-aircraft crews, the damaging effect was the repeated visual transition between bright and dark areas rather than simple darkness alone.