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Double rainbows are not only rare, but also one of the most extraordinary phenomena created by nature.
A double rainbow appeared in the sky of Hanoi on the afternoon of July 22 (Photo: Trieu Duong).
On the afternoon of July 22, many people in Hanoi witnessed an amazing natural phenomenon when a bright and clear double rainbow appeared in the sky.
Double rainbows are not only rare, but also one of the most extraordinary phenomena that nature has to offer. Typically, rainbows occur when sunlight hits raindrops, causing refraction and dispersion. Long wavelengths (red) are bent more than short wavelengths (blue), creating a brilliant rainbow in the sky.
The double rainbow phenomenon occurs when the Sun’s rays reflect “a second time” with raindrops (Photo: Tien Tuan).
A double rainbow, also known as a “twin” rainbow, occurs when the Sun’s rays reflect a “second time” off of raindrops, creating a second curve in the same plane as the primary rainbow. The light that enters the raindrop and is refracted at the surface does not exit after hitting the back of the raindrop, but is instead refracted a second time, creating a secondary rainbow.
The secondary rainbow is characterized by the inverted colors of the primary rainbow. The light from the secondary rainbow is also dimmer and harder to see because much less light is refracted a second time. The shape and position of the secondary rainbow are also different, being about 10 degrees away from the primary rainbow and radiating at a 50-degree angle.
Double rainbows are so rare that anyone who has the chance to witness them is considered extremely lucky. In some Eastern cultures, double rainbows also represent good luck and happiness.