Double Rainbow
is one of natural phenomenon where you get a wonderful sight there are two spectacular natural displays at
one time.
Double rainbow is used when both the primary and
secondary rainbows are visible. In theory, all rainbows are double rainbows,
but since the secondary bow is always fainter than the primary, it may be too
weak to spot in practice.
Double rainbows are formed when sunlight is
reflected twice within a raindrop with the violet light that reaches the
observer's eye coming from the higher raindrops and the red light from lower
raindrops.
This means the sequence of colours is inverted
compared to the primary rainbow, it is seen on the same side of the sky as the
primary rainbow, about 10° outside it at an apparent angle of 50–53°. As a
result of the "inside" of the secondary bow being "up" to
the observer, the colours appear reversed compared to those of the primary bow.
The dark band between the two rainbows is known
as Alexander's band, after Alexander of Aphrodisias who first described it in
200AD.
The band forms because between the deviation angles
of the primary and secondary rainbows none of the sunlight is scattered by the
raindrops towards the observer giving the band of dark sky.
͍➯Place where double rainbow have been seen
1. Sydney, Australia
2. White Sands National Monument, New Mexico
3. Skogafoss, Islandia
4. Alberta, Kanada
5. Bla Bheinn, Skye, Skotlandia
6. Chicago, Ilinois
7. Month Saint Michel, Perancis
8. Victoria Falls, Afrika
9. San Francisco Bay Bridge, California
10. Garden of the Gods, Colorado
11. Mount Alyeska, Alaska
12. Beijing, China
2. White Sands National Monument, New Mexico
3. Skogafoss, Islandia
4. Alberta, Kanada
5. Bla Bheinn, Skye, Skotlandia
6. Chicago, Ilinois
7. Month Saint Michel, Perancis
8. Victoria Falls, Afrika
9. San Francisco Bay Bridge, California
10. Garden of the Gods, Colorado
11. Mount Alyeska, Alaska
12. Beijing, China
And many more.
