Since the value of µ for water is about, it follows that n must be at least unity for a rainbow to be formed; there is obviously no theoretical limit to the value of n, and hence rainbows of higher orders are possible.
Water shot from the bottom of the canyon, forming hundreds of tall columns whose mist cast rainbows in the bright moonlight.
PerEwpa, literally " things in the air," from yerb., beyond, and a€ipav, to lift up), a term originally applied by the ancient Greeks to many atmospheric phenomena - rainbows, halos, shooting stars, &c. - but now specially restricted to those luminous bodies known as shooting stars, falling stars, fireballs and bolides.
The Vernal, about half a mile below the Nevada, is famous for its afternoon rainbows, At flood-time it is a nearly regular sheet about 80 ft.
In the first class we have halos, and coronae, or "glories," which encircle the luminary; the second class includes rainbows, fog-bows, mist-halos, anthelia and mountainspectres, whose centres are at the anti-solar point.