Strange Colored Cloud

[Bodryn]

This strange colored cloud appeared late one afternoon last year and lasted for about half an hour or so until sunset. It might seem as though I was using a circular polarizer but no filter was used at all. I could speculate as to the cause of this but maybe others have a scientific explanation.

[watermarkphotography]

I have seen one like this before. Very cool. I read that it is caused by ice crystals, Though I saw it in the summer in Seattle.

[Penguin_101_1]

Was it like this?
http://michaelg.fotopic.net/p3127296.html
If it was then here is what causes it:
Michael,

I have seen this type of thing before, but I didn't know it had an official name.

What I think is going on...the lumpy, flat cotton-ball type cloud deck is proabably made up of microscopic super-cooled water (water...in nature...can
actually exist in liquid form at temperatures well below freezing). When
another microscopic particle (called condensation nuclei) is introduced into this cloud, the super-cooled water vapor is attracted to it (or condenses on
it), and then the water vapor turns to ice. Once enough condensation occurs,
the particles become heavy enough that they begin to fall.

The hole you see in the cloud is from an area where the condensation nuclei has been introduced and the cloud particles have condensed out. Where does the condensation nuclei come from? They could be ice crystals from a cloud deck ABOVE the super-cooled water clouds. In your picture, there is wispy cirrus clouds in the hole...these are certainly ice particles...they could be above the cloud deck with the hole, and they could be the source of the condensation nuclei. Or, they could be the ice crystals that are falling to create the hole. It's tough to tell.

Another source of condensation nuclei would be particles from airplane exhaust. When I have seen this, it has been when jets have flown through the clouds.

I hope this isn't too confusing, but if you have any further questions please write again.

Incidentally, you captured another phenomena on this picture. On the lower left hand side, above the horizon at the same height as the sun, there is a bright spot in the clouds. This is a sun dog. Often, you will see two of them...one on each side of the sun, and at equal distances from the sun.

Scott Truett
NOAA - St. Louis

[Bodryn]

I rechecked the data on the photo and it was from last March. I took about 90 photos of this general cloud area over about a 30 minute period. If anybody is interested I could make more of these available. I do know sundogs very well, having grown up in northwestern Minnesota and they are often visible on cold sunny January days, complete with a ring around the sun. However the rainbow effect on those is always organized and predictable. What I found unique about the cloud in the March photo was the random unstructured color of it.

[TJ]

Saw one here in Nova Scotia recently.