Krypton lamp. Krypton lamps are arc lamps (light is produced by electricity flowing between two electrodes) that have been filled with krypton to produce very bright light. The light can penetrate through fog to over 300 metres away, so these lamps are used to light aeroplane runways at night. A krypton lamp containing the isotope krypton-86 was also used to determine the precise length of one metre by having its light wavelengths measured.