Fog bow

 

I have seen and posted about fog bows before but this one caught me by surprise. There was no fog. Reading this article, I now know that I was seeing the red at the top and the blue at the bottom. It suggests that the water vapour that was in the air was of tiny size and this caused diffraction so that all the middle colours ended up in the same direction and thus appeared white to me. At the time of viewing, there were dark clouds over Scotland and a hour later we were enveloped by a cloud front that dropped a small amount of snow on us.