Leuchtende Nachtwolken / Noctilucent Clouds

Inhalt / Contents

Englischer Text / English version
Deutscher Text / German version
NLC-Klassifikation / NLC classification (in German)
Querverweise / Links


NLC in der Nacht 26./27.Juni 2003 von Marquardt aus. Die hellsten (und zugleich letzten!) NLC der Saison 2003 traten in den Nächten 11./12. und 12./13. Juli auf.
NLC in the night 26/27 June 2003 seen from Marquardt. The brightest (and last!) NLC of the 2003 seeason were observed in the nights 11/12 and 12/13 July.

Noctilucent Clouds

Clouds of this unique type have been first reported in 1885 by Backhouse, Jesse and Leslie. Jesse initiated an observing program, including photographic methods. The surprising result was the height of these clouds - they are situated 83 km above the Earth's surface. This value has been confirmed for NLC ever since. Still there are several aspects of the NLC which are not yet understood. For example, there seem to be relations to the

NLC can be observed between mid May and mid August in the northern hemisphere when the Sun ist between 6 and 16 degrees below horizon. Look for more details at Tom McEwan's NLC page. There you also find a summary of recent NLC observations.
Other information on NLC and related phenomena, such as Polar Mesospheric Summer Echoes (PMSE), is available from a page of the Swedish IRF..
Furthermore, there are NLC report summaries from observers of the AKM in 1995, 1996 and 1997
The first photo shown here (above) is from Sirko Molau, Berlin, taken on June 22, 1997.
The second image is from a synchronous series of NLC photos taken from Potsdam, about 25 km southwest of the location where Sirko took his photos from. An analysis of this series is under preparation.
The recent NLC-seasons were rather short. They started only in mid-June while in previous years NLC were seen as early as end May or so. Normally the last NLC of a season are visible around mid-August. Since there are about 20 regular observers of NLC in the AKM group (some at meteorological stations) the low number of NLC reports can hardly be explained by bad conditions or by accident. It is thought that an increase of Solar activity could cause an increasing energy input into the Earth's atmosphere, which then could rise the the temperature at the Mesopause. As a consequence, the low temperatures for the existence of NLC could not be reached. This would lead to an anti-correlation between the frequency of NLC and Solar activity. Right now were are in the phase of decreasing Solar activity. However, we do not know the current conditions in the Mesopause, and it will be interesting to see how frequent and intense NLC occur this year. Further images of NLC can be found e.g. on the NLC page of the Fachgruppe Atmosphärische Erscheinungen or in the "Karlsruher Wolkenatlas".

Other atmospheric optical phenomena are also collected in Bernhard Mühr's cloud atlas, for example various halo forms, twilight phenomena, a fogbow ...