Abstract

Noctilucent clouds (NLC) are ice clouds located in the high latitude summer mesosphere at heights between 81 and 85 km. The formation process is not well understood but it is thought that a growth cycle is activated by the extremely low temperatures of the mesopause region, typically 120 to 130 °K. This process involving condensation nuclei transported into the mesosphere from meteoritic debris and the upwelling of water vapor into the mesosphere from below produces condensation of ice upon particles within the supersaturated region lying several kilometers below the mesopause temperature minimum.

© 1991 Optical Society of America