Where is the sun always positioned when you look at a rainbow?

A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicolored circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun.

Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the sun to the observer's eye.

In a primary rainbow, the arc shows red on the outer part and violet on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it.

More Info: en.wikipedia.org

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6 Comments

Fred Mayes

I have heard some say they have seen rainbows without having the sun at their back, but according to physics this can't happen. A rainbow is formed by light being refracted off of the back of a raindrop and then reflected back at you at an angle of 40 to 42 degrees. A double rainbow can be formed by a double refraction at an angle of 50 degrees. It is possible to have a full moon create a "moonbow", but it is usually so faint you can't see colors - just a band of light. Since the rainbow is formed at a specific angle, that angle forms an arc about the observer. If you are in an airplane and are lucky enough to see a rainbow (as I have), it will be a full circle below you and the shadow of the airplane will be in the center. I saw a Thomas Moran painting once with the sun and a rainbow both visible - not gonna happen. I believe the only way you could see something like that would be if there were a huge highly reflective object behind you that would serve as a light source. IMHO.

earlepg

I never paid attention to where the sun was, but being forced to think about it, my answer had to be to put it behind me for the best view.

Kathryn Cavanagh

Jehovah's vow to Noah to never flood the earth again. BUT watch out for the hailstones and fire..!!

Steph

I've seen rainbows to the left of me and to the right of me as well as in front and behind. The sun is thus not always behind me, but opposite from where the rainbow is.