Rare Noctilucent Clouds Seen Over Armagh

An image of the noctilucent clouds observed on the night of 19th/20th June over the Mall in Armagh, recorded by Astronomer John Butler

Rare noctilucent or "night shining" clouds were observed over Armagh on the night of 19th/20th June. These silvery, highly structured clouds take many forms, ranging from delicate feather structures to streamers, ripples and waves, and are only seen occasionally, always after dark, during the summer months May to August. Scientists believe that they are caused by sunlight reflecting off tiny ice crystals in the mesosphere, a region of the EarthтАЩs atmosphere lying high above the stratosphere, at a height of around 80 kilometres.

Extract of Romney RobinsonтАЩs report of a similar phenomenon in the ObservatoryтАЩs meteorological records for 1st and 4th May 1850.

Noctilucent clouds are a relatively recent atmospheric phenomenon. They were first reported in 1885, though there is an earlier mention of a similar phenomenon in a report by the Armagh ObservatoryтАЩs third director, The Revd Thomas Romney Robinson, in early May 1850. His handwritten note in the ObservatoryтАЩs meteorological archives for that month records his observation of "strange luminous clouds in the NW, not auroral". There is also a suggestion that the frequency of noctilucent clouds has increased in recent years and may be linked to global climate change and possibly also to the incidence of meteoroids in the EarthтАЩs upper atmosphere. Meteoroids can deposit dust particles and associated meteoric "smoke" in the mesosphere, which can act as condensation nuclei for the observed tiny noctilucent cloud ice crystals.

See also:
Video by Paul Evans
Image by Paul Evans
Possible Observations of Noctilucent Clouds by Thomas Romney Robinson - PDF
Time Lapse Movie of Noctilucent Clouds in 2006

For more information contact Mark Bailey at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; mebarm.ac.uk

Last Revised: 2014 June 23rd