First Alert Weather Academy: How do rainbows form?

First Alert Weather Academy: How do rainbows form?

SAVANNAH, Ga. (WTOC) - Rainbows are one of nature’s most beautiful creations. We’ve all seen them in the sky after the rain ends.

Today, we’re going to discuss how they form.

To see a rainbow, you need three things:

  1. Sunlight at your back and low in the sky.
  2. Water droplets in front of you.
  3. You, standing in between the two.

Sunlight appears to be white but is made up of many different colors. Some we can't see and some we can. They range from infrared to ultraviolet.

The colors that the human eye can see are called visible light. An easy way to remember the colors is ROY G BIV (Red, Orange, Yellow, Green, Blue, Indigo and Violet).

Each color has a different wavelength, so as it enters the water droplet it slows down at different speeds. This allows the light to get refracted or bent at different angles between 40º-42º.

The light then reflects off the back of the droplet towards the observer. When the light exits the droplet and hits air again, it gets refracted a second time.

If you're lucky enough you can sometimes see a double rainbow. This occurs when the sunlight gets reflected twice in a droplet. You'll notice that the second rainbow colors are reversed and always lighter than the primary rainbow.

Rainbows are always in the shape of a full circle, but we can’t see the bottom because the Earth gets in the way.

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