On the Possible Anticorrelation of Polar Mesospheric (Noctilucent) Clouds and Aurorae.

The study of noctilucent clouds NLC is one century old, yet the origin and nature of these clouds is still uncertain. It is known that these clouds form in the cold, high latitude summer mesopause region where temperatures can approach 110K. Their association with the very cold air in this region supports the theory that they consist of water ice particles. It has been suggested that NLC are anticorrelated with aurorae since aurorally induced effects at or near the mesopause may lead to processes which retard or altogether inhibit NLC formation. This study will review some general characteristics of NLC, polar mesospheric clouds PMC and aurorae and then discuss several ways in which aurorae may interact with these clouds.