Rainbows - Full Circle or Arc?
You've probably heard there's a pot of gold at the end of the rainbow, but do rainbows actually have ends? Often it looks like the rainbow continues past the ground as if it should be making a full circle. So which is it: is a rainbow an arc or a full circle?
In a recent article by EarthSky, you can see images like this of a full circle rainbow. They are very rare and are only seen under specific viewing conditions. The height of the sun is the main factor in how much of the rainbow arc you see. The higher the sun, the lower the top of the rainbow which means you will see a smaller part of the arc. If the top of the rainbow is higher, you should be able to see more of it. That leads us to the other important part: your height. The higher up you are, the more of the arc you can see. Pilots in airplanes and mountain climbers report seeing the full circle of a rainbow, but those sightings are very rare.