SPA Aurora Section

Nacreous Clouds

NACREOUS CLOUD DISPLAY: 1996 February 16-17.

Nacreous, or, ‘Mother Of Pearl’, clouds differ from noctilucent clouds (NLC’s) in that they occur much lower in the atmosphere at around 25 km altitude, as opposed to NLC’s massive height of 82 km. However, nacreous clouds share one similarity with NLC; they are best seen in twilight when, due to their considerable height, they remain sunlit long after the sun has set.

Nacreous clouds can be very colourful, typically exhibiting subtle ‘rainbow’ tints of blue, green and pink, resulting from the reflection and refraction of sunlight through the cloud-sheet. Nacreous clouds are normally only seen during winter from northern latitudes and from the UK are a very rare phenomenon (much rarer than the aurora and NLC).

On the evening of February 16-17, 1996, an unusually bright and colourful display of nacreous cloud was seen over Scotland and England. Several SPA Aurora Section members witnessed and reported this unusual event. The images below are a selection of members’ photographs taken from between 1645 - 1800 UT on this memorable night:

Diana Wilcox, Stockport.

Dorothy F. King, Ashbourne.

Paul Kenealy, Knaresborough.

Dusko Novakovic, Northampton.

For more Nacreous Clouds images, see photographs by John Bolton of the MAS.

Created by Michael Oates Last modified 3 February, 2001