Rainbow

You can feel when a rainbow's going to appear but you never know exactly where or how intense. or even how long it's going to last. This was quite a vivid double rainbow, but only lasted a few minutes.

We went for a walk in the afternoon and had missed some of the sunny weather. So I was disappointed about that, but we got caught in a heavy shower and then the sun came out and produced this great phenomenon. 

Rainbows occur when there are water droplets in the air and the sun shines behind you at a low angle. So you see rainbows in the west in the morning and the east in the afternoon. We were facing east when we saw this.

In a double rainbow the second arc has the order of colours in reverse, like a mirror image. The dark sky between the two rainbow is called Alexander's Band named after Alexander of Aphrodisias who first described it in 200 AD.

Every rainbow is theoretically a full circle but you can't see that from the ground. You need to be higher than the horizon to see this. So next time I'll charter a helicopter!