By: Francesca Master
Rainbows play a significant role in the story of Saint Patrick and, therefore, are one of the main symbols of his holiday. Almost everybody has heard stories of the leprechaun at the end of the rainbow and, perhaps, followed one with the goal of finding a pot of gold. But what is it that causes these majestic phenomena to happen?
A rainbow forms when sunlight travels through a raindrop at a 42-degree angle. Contrary to popular belief, rainbows don’t actually exist in the sky but rather are an optical illusion. Whether or not one sees one depends on where a person is standing, as well as the relative location of the sun.
A rainbow forms because of the refraction and reflection of light; both involve a change in the wave’s direction. When light goes into a water droplet, it is refracted and then reflected by the back of the droplet. When the light leaves the droplet, it gets refracted at multiple angles, causing a spectrum of color, including red, orange, yellow, green, blue, indigo, and violet. Red has the longest wavelength of visible light, about 650 nanometers, while violet has the shortest, about 400 nanometers.
Although people think rainbows are just a curve, they are actually full circles! On the ground, you can only see the light’s reflection above the horizon, and every viewer sees it differently. When you are in a plane, you are more likely to see it as circular.
There are also many variations of rainbows. Double rainbows occur when light gets reflected twice inside a rainbow, forming a second rainbow above the first where the colors are reversed, with red on the inside and violet on the outside. Another type of rainbow is a reflected rainbow, which shows up on a body of water. It’s created by light getting reflected on the water’s surface.
Rainbows have long been one of nature’s most beautiful and inspiring symbols. And, while there may be no pot of gold sitting at the end of one, it is still worthwhile to take a moment and look up when you see one.
Source: https://education.nationalgeographic.org/resource/rainbow/
Featured Image Source: National Geographic
The Fieldston Science Bulletin 
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