Flares generally produce their light through the combustion of magnesium metal, sometimes colored by the inclusion of other metals. Calcium flares are used underwater for illumination.Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery, or deployed by handheld percussive tubes. Flares may also be dropped in the water to illuminate submerged objects.In the civilian world, flares are commonly used as distress signals, and may be ignited on the ground or fired as an aerial signal from a pistol-like flare gun. Flare guns are commonly found in marine survival kits.
