Or Nacreous clouds to be more exact.
These are rare and are usually seen within 2 hours of sunset or right before dawn. I took these pictures today around 3 pm (yes, that is our sunset at the moment….. it is completely dark and the moon is out as I am writing this. Welcome to the Arctic Circle 😀 ).
Anyways, what is a Nacreous cloud, you ask? It is a cloud way up high in the lower stratosphere about 15 to 25 km high ( 9 to 16 miles for our American friends), as a comparison I can tell you that planes usually cruise at an altitude of about 10 km. The reason why they are so bright is because of their height. They are still lit up by the sun whereas everything else is not. They appear when the temperature in the lower stratosphere sinks to a whopping minus 85°C -Brrrrrrrrrr- (that is minus 121°F) and are actually clouds of ice particles.
Why are these clouds rare? It is not that often that the temperature sinks to this level even in the stratosphere. On top of that, it is not that common that clouds form in the stratosphere. And on top of that, the cloud needs to have similar sized ice crystals which make up for the cloud. On TOP of all of this, it has to be somewhat of a clear sky to see them.
Where can they be seen? North! And winter, we got both of those down :).
~ Rebecca ~
- The stratosphere is part of the atmosphere which is divided in three levels. The troposphere – this is were most weather forms -, the stratosphere and then the mesosphere.
- So far this winter I have fallen down 8 times on the icy snowy roads.