|NLCs Continue! - Noctilucent cloud display July 21/22 '09. Jari Luomanen (more of his images) took this 180°+ panorama at Kangasala, Finland. ©Jari Luomanen
NLCs have been more frequent in recent years and July has seen many spectacular displays over Europe and the northern USA. This one extended over several European countires.
NLCs are composed of ~0.1 micron ice crystals and require temperatures below -123°C to form. Cooling of the mesosphere and/or increased water vapour transport to the cloud altitudes of 50 - 53 miles is indicated.
Scan the browser window over the gravity wave induced intricate structure captured by Jari.