Rainbow Spotting

During heavy rainfall and Sun at the same time on Friday 22nd August 2008, at around 6pm, I looked around the sky for a rainbow, and there it was at the back of my house, with more bands of colour than I can remember ever seeing.

“A supernumerary rainbow is an infrequent phenomenon, consisting of several faint rainbows on the inner side of the primary rainbow, and very rarely also outside the secondary rainbow. Supernumerary rainbows are slightly detached and have pastel colour bands that do not fit the usual pattern”. Is this photo below a supernumerary rainbow? It does seem to have a lot of colour bands.

The main image even shows a second rainbow trying appear above the main one, this is called simply a double rainbow. Two rainbows in the same sky is also something I have never witnessed before.

Apparently secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50°–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside.

It is remarkable how quickly a rainbow can appear and how quickly it can fade away and lose it’s intensity and the number of bands of colour.

Rainbows are optical illusions and meteorological phenomena that cause a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth’s atmosphere. They take the form of a multicoloured arc, with red on the outer part of the arch and violet on the inner section of the arch. More rarely, a secondary rainbow is seen, which is a second, fainter arc, outside the primary arc, with colours in the opposite order, that is, with violet on the outside and red on the inside.