Four Types of Rainbows Over Taiwan

May 19, 2022


Photographer: Chiahui Lee

Summary Author: Meiying Lee; Cadan Cummings

The photo above features multiple types of rainbows visible after a rain event near Lukang, Taiwan. If you look closely, there are at least four rainbows in the photo. The first two are the primary and secondary rainbows visible in the center of the image. Primary and secondary rainbows are the most common types of bows and are created when light is reflected and refracted by raindrops suspended in the air. The difference between primary and secondary rainbows is the incoming sunlight is reflected only once inside the rain drop for primary bows, whereas for secondary bows, the light is reflected a multiple time. This additional reflection also causes the secondary bow colors to appear reversed.

Curving between the primary and secondary bows is a reflection rainbow produced by sunlight reflecting off calm water or wet sand. Looking at the waterlogged road ahead, there is a fourth reflected rainbow noticeably on the shimmering pavement surface. Like the secondary rainbow, reflected rainbow colors appear reversed. However, this additional reflection was due to light being scattered off land features, as opposed to within suspended raindrops. Furthermore, if you look closely, you can also see supernumerary rainbows on the inside of the primary rainbow.