Bow-Spotting

From a picture by Nola Davies, Camden Haven, NSW, AU, as analyzed by Dr. Les Cowley:

Dr Cowley explains: 'All rainbows are made when sunlight is reflected inside falling raindrops.

'The bow we see most often and the brightest one in Nola's picture (1) comes from just one reflection inside almost perfectly round raindrops. All but the largest raindrops are round and not at all like the teardrops commonly pictured.'

He continued: 'The outer bow (2), the one we also see sometimes, comes when sunlight reflects twice in each raindrop.

'Now we enter the territory of rare and unusual events.

'A third bow (3) crosses the two brightest ones. That was made from sunlight first reflected upwards from the river before reflecting once again inside the raindrops.
'To raindrops it looks as though a second sun is shining upwards from the water. To have a chance of seeing this bow you need a large sheet of calm water in front or behind you.

'The bright upside-down bow in the water (4) is not an ordinary reflection of the one in the sky but it is made by rays of light from a different set of raindrops bounced upwards by the river.

'Bow 5 needs even more reflections two from the river and one inside the raindrops.'

The last rainbow is barely discernible, but Dr Cowley insists it is there if you look hard enough.

He added: 'Bow 6, of which Nola's camera has caught just a faint fragment, is from one river reflection and two more inside raindrops.

'It is so faint because of the many reflections and because its colours are spread out.'