A Double Rainbow
A double rainbow
October 18th at 6:15 pm in Barrie
a beautiful double rainbow appeared and gone within 15 minutes.Barry's Response
- Thanks, Tammy. Rainbows come in a lot of different variations. Wikipedia has them listed.
You've captured two distinct rainbows, where you can see the full spectrum in each. They'll also notice that the colors appear in reverse order in the second rainbow. Why? The pattern flips because of two reflections inside the drop. Sometimes you can see a third arc. The sky between the rainbows is darker than the rest.
How does a rainbow form? The refraction effect. We get light directly from the sun, and it's mixed with all the colors we know to give it its yellow hue. Transparent liquids or solids let light through, but at a slower speed than air. In addition to slowing down (a little), it bends when it enters an object, like a prism or water droplet.
You'll get used to it. The different colours, wavelengths actually,
bend at different angles and come apart to form the rainbow pattern, like on the old Pink Floyd album.
The light enters sphere-shaped water droplets, like those floating in the air after a rainstorm, and then reflects off the inner backside of the sphere. At one end of the spectrum, red is bent 42 degrees, and violet is bent 40 degrees. Meteorology and optics.
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If we viewed a double rainbow with a keen analytical mind and a deep understanding of its underlying physical principles, what might we discover?
Maybe like a physicist who develops technology and was curious about everything. To explain how a double rainbow forms, one might explain how a single rainbow forms:
- When sunlight enters a raindrop, it slows down and changes direction because of the change in refractive index (from air to water).
- Raindrops reflect light off their inner surfaces.
- In the transition back to air, the light undergoes further refraction as it exits the raindrop. The varying indices of refraction for different wavelengths also cause the light to disperse into its component colors (red, orange, yellow, green, blue, indigo, and violet).
- When light rays strike the inside surface of a raindrop at a certain angle, total internal reflection occurs, reflecting the light back inside.
- Eventually, the light exits the raindrop, forming a circular rainbow with red on the outer edge and violet on the inner edge.
Here's how we explain the double rainbow
- The secondary rainbow happens when the light reflects twice inside the raindrop before it leaves. Due to this double reflection, violet is on the outer edge and red is on the inner edge.
- A secondary rainbow appears at a larger angle (approximately 50-53 degrees) than the primary rainbow (about 42 degrees).
Double rainbows have angles and colors due to mathematical and optical intricacies.
Due to his scientific background, an expert in this field could appreciate the phenomenon both theoretically and empirically, showcasing the beauty and elegance of nature.