Nacreous clouds 1

This photograph and the next (both by Lee) show a spectacular display of nacreous clouds seen over Leeds and much of northern England in 1996, showing strong irisation. The event was unusual enough to appear on the news broadcasts of the day. Nacreous clouds are extremely high (about 25km), and like aurorae are often regarded as astronomical rather than meteorological phenomena.

Note well: the colours are real -- no enhancement has been done, apart from removal of some telephone wires and minor scanning blemishes (see this article for more details).

Both this and the next image are scans from original prints, taken with a Minolta camera.

This display generated much interest (and not a little misreporting). Nacreous clouds are rare, but these definitely were nacreous clouds, and not the much more common noctilucent clouds. There was a discussion on the subject at the time in the sci.astro.amateur newsgroup entitled "WIERD [sic] CLOUDS OVER LEEDS (UK)", with one particularly interesting and knowledgeable contribution coming from Alan Pickup of the Royal Scottish Observatory (and currently the writer of the Guardian's regular 'Skywatch' astronomy column). It's the 11th message in the thread, and here's an extract:

However, the clouds seen widely on February 16 were _not_ noctilucent clouds. Rather, they were the very much rarer nacreous clouds, also called Mother of Pearl clouds. These, too, are ice crystal clouds, but at about 25 km altitude where they hang like vast chandeliers refracting sunlight in a rainbow of colours. Having seen both types, I can say that nacreous clouds I saw were much brighter and more colourful than noctilucent clouds. [...]

More pictures of this particular event can be seen at the following sites:

• Martin Brown
• John Bolton
• British Antarctic Survey
• For further information, explanations and photographs, visit the splendid Atmospheric Optics web site.

Image details