The heavy rains yesterday left a spectacular rainbow. The images flooded Twitter and Facebook with many of them showing a double rainbow.
Many of us remember that acronym back in grade school ROY-G-BIV: that's red, orange, yellow, green, *blue, indigo, and violet. The white sunlight contains all these colors all the time, but only under special circumstances do we get to see them, and July 8th we saw them in very big fashion.
Sunlight shines through the water droplets in the air, then back into your eyes at a 42 degree angle to the light. The one above it is at 52 degrees.
After the storm passed us in the east we have a bunch of water vapor left over, and the sun is behind us in the west; perfect ingredients for a rainbow.
It has that curved shape because of the way the light enters your curved eye. Also if your look close enough, you can see the second rainbow above it in reverse order.
So the rainbow above is the second reflection within the same group of water droplets at a different angle. Many rainbows are found on a much smaller scale:
One of the simplest ways to produce a rainbow is with a garden hose. Just get it to make that wide spray, have your back to the sun, and you can see it.
The more water droplets the bigger the rainbow. This one is seen with millions upon millions of droplets that are constantly moving around, so at every instant, you're looking at a different image.