NLC's
What are NLC's?
Noctilucent clouds (popularly referred to by the abbreviation "NLC") are high atmosphere cloud formations thought to be composed of small ice-coated particles; their precise nature remains a mystery. They form at very high altitudes - around 82 km above sea level - and are, thus, a quite separate phenomenon from normal weather or tropospheric cloud.
Source of information: Noctilucent Cloud Observers' Homepage
Click here to see Stan Richard's NLC photos
Lichtende nachtwolken (Astronova.nl)
