I snapped the shot which I thought was interesting. Throughout the week we had noticed several such rainbows in many places, caused by the sun's rays being refracted just like a prism on striking the windows. My mind recalled the famous acronym I learnt at school when white light entering a prism is split into all the colours of the rainbow.
Richard Of York Gave Blood In Vain
Red, Orange, Yellow, Green, Blue, Indigo, Violet
But windows panes are not prisms - they are just even sheets of glass, surely! Not so these:
. . . . . . and another shot from the inside:
Ah!! yes . . . . . . you now know the answer to the question when is a window a prism? When it has a bevel in it of course, and there are now 9 bevels shapes in 3 fanlight windows we had installed. The sunlight strikes the bevel and acts just like a prism, and because there are 9 bevelled diamonds the phenomena causes rainbow images to appear in interesting shapes. The images move too as the Earth rotates, which is a bit eerie. I can't wait for the summer when we get more sun. But I hope the bevels do not act as magnifying glasses as well - remember using magnifying glasses when we were kids when we wanted to start fires in the garden, using the sun's rays on a sheet of paper?
The original three fanlight windows all had to be replaced because the seals had broken inside the double glazed units, causing a misty film which happens when such windows eventually break down. I am an agent for a local window company so they fitted them for me two weeks ago.
Oh and just in the background of the last shot we can see my blue tit box - but no blue tit this time. We see them frequently but they are flitting about all over the place and sometimes don't return for a few days. Here is a close up shot of the bird house with the new bevel diamond showing refraction of the vegetation: