Iridescent cloud

Despite a very cold winter, there has been no nacreous clouds this winter. This is the only display that’s coming close. Alas, it’s not nacreous. The sun is down, they shine brightly, they are stationary, but are simply a bleak indication of true nacreous clouds.

Last time was in 2008 and the extent and variety of the iridescence was jaw-dropping. It was so strong and unusual that it hit the news, and even Spaceweather was asking what was going on.

Opposed to 2008, this winter was very stable and cold as the polar front was mostly south of Norway – very few low pressures coming in from south west. When the wind is coming from this direction, it will slam into the long mountain range which divides the eastern and western part of southern Norway and be forced high up into the stratosphere – more than 15 kilometres high. And only when the stratosphere is extremely cold, like it has been this winter, can the nacreous or mother of pearl clouds form.

As this is late March, its seems to be yet another year with no mother of pearls in the sky.


Last updated on 15 December 2020