Rainbow Unicorn
Light and physics are typically more responsible for rainbows than unicorns
Although some rainbows might come from the gassy posteriors of flying cartoon unicorns, most are produced when sunlight bounces off of water droplets in front of a viewer at a 42 degree angle. These water droplets might be rain in the atmosphere, fog or drops scattered due to sea spray or waterfalls. Rainbows are the result of the refraction and reflection of light, processes that change a lightwave's direction; refraction appears to bend a light wave while reflection is the phenomenon where a lightwave appears to bounce back towards the source. Light entering a water droplet is refracted and then reflected by the back of the droplet. As this reflected light leaves the droplet, it is refracted again, at multiple angles.
The appearance of a rainbow depends on where the viewer is standing in relation to the source of light, typically emitting from behind the viewer. As such, no two people will see the exact same rainbow. The center of a primary rainbow is known as the “antisolar point,” a point exactly opposite the sun. Rainbows are actually full circles, the antisolar point being the center of the circle. Viewers on the ground can only see the light reflected by raindrops above the horizon, resulting in an arc shape. However, from above the horizon, from a plane, for example, it is sometimes possible to see the entire circle of a rainbow.
Huh. I'd heard there's always a double rainbow, but the inner one is often too faint to see. I'd never heard it's a circle that you might see if you're high enough.
Ta, Martini. I have some wonderful rainbow photos. Maybe I'll post one sometime.