On February 20 and 24, 2013, unusual clouds which looked like NLC (noctilucent clouds) were observed by the pilots Terry J. Parker above Birmingham, UK, Nikolay N. Nikolaev and Egor C. above Moscow, Russia (picture at top).
In the AKM forum (AKM = Arbeitskreis Meteore/ Meteor Workshop) there were discussions on what could have been the reason for this unusual phenomenon.
- Polar Stratospheric Clouds can be excluded as a reason because the stratosphere was too warm at the time the observations were made (1–2).
- MAARSY (Middle Atmosphere Alomar Radar System) in Andenes, Norway, recorded strong echoes in the mesosphere. Weak echoes have also been recorded at Kühlungsborn, Germany. Mesospheric winter echoes are common, but up to now there are no special observations recorded which were connected to these echoes.
- There was a full moon on February 25, so high cirrus clouds illuminated by the moon cannot be excluded as a reason.
- The most probable explanation for the phenomenon is, however, that the clouds had been caused by the meteor which hit near Cheljabinsk, Russia, on February 15. A recent study by Kathryn Hansen shows that this cloud of smoke travelled around earth in an altitude of about 40 kilometres. This fits with altitude measurements made in Wales, which showed that the unusual clouds had formed at altitudes between 35 and 38 kilometres.
Another article to this Topic: “Noctilucent clouds in october ?”