A red rainbow gave Finnish fisherman the 'creeps'. Are they real? How do they form?

Rainbows contain seven colours, there is no two ways about it - red, orange, yellow, green, blue, indigo, and violet. That is what makes up the essence of these optical illusions that form when the sun's rays scatter raindrops. Rainbows have some variations as well, such as those that appear over water, called the reflected rainbows, and moonbows, a rare rainbow created by moonlight rather than sunlight. Every time, you see the vivid colours a rainbow is supposed to contain. But, have you heard of a monochrome rainbow - that which only shows one colour? In a letter published in an 1881 issue of the science journal Nature, physicist and electrical engineer Silvanus P. Thompson described this incredible phenomenon that he saw four years ago. He wrote that the rainbow made an appearance at sunset, and he could only see red and orange colours instead of the whole spectrum. He saw it at sunset, the time such rainbows typically make an appearance. Also Read: Glitch 11,320 feet below the ocean? Scientists say 'ghost particle' from deep space crashed into Earth

How do red colour rainbows form?

There is nothing different about the creation of a red rainbow. It forms just like a regular full-spectrum rainbow. Rainbows don't physically exist, but make an appearance when sunlight passes through drops of water at a 42-degree angle. The visible light spectrum has different wavelengths of light, which create the different colours we see in the rainbow. When sunlight passes through a water droplet, each wavelength reflects at a different angle, thus creating the rainbow band. With red rainbows, only the red colour is visible. They happen either at sunrise or sunset, when the sun is closest to the horizon. The sun's rays have to cover a longer distance from here, and so, only the longer wavelength reaches us, with the others ending up scattering in the sky. Since red is the longest wavelength, we only see red. Also Read: Déjà vu: A glitch in your brain or did your consciousness travel to the future?

Red rainbows are rare, but were seen twice in 2020

This particular incident of a red rainbow is not the only one recorded. In 2020, a fisherman in Finland saw one over the lake in Paijanne Tavastia, about 160km north of Helsinki. "It started raining, and this rainbow appeared. It was pretty amazing because you could see it from start to end, but also it was only red," Avie Junno said, adding that it gave him the "creeps". However, he managed to take a picture of the illusion in the sky. Someone also reported seeing a partial red rainbow in Botswana the same year.