Bright primary rainbow over Schlägl, Austria.
The sky is brighter inside the bow because rainbows are disks of
than sets of coloured rings.
Outside the primary there is a fainter secondary bow.
Imaged by Karl Kaiser (site)
on August 28, 2002.
©2002 Karl Kaiser, shown with permission.
see a rainbow we need sunshine and falling rain. Rainbows are rarer
than might be thought. In any one place in rainy England there
are fewer than ten bright ones in a year. Halos occur
much more frequently.
Early morning and late
afternoon are the best times to see them because the sun must not
high. Rainbows are always opposite the sun and their centres
are below the horizon at the the antisolar point. The lower
the sun the
higher is the bow.
Red is always outermost in the primary bow with orange, yellow,
green and blue within. Occasionally, when the raindrops are small,
arcs of electric greens, pinks and purples lie just inside
the main bow.
rainbow is not just a set of coloured rings. The sky inside is
bright because raindrops direct light there
too. The primary bow is a shining disk brightening very strongly
towards its rim.