When we think of rainbows, most of us imagine a colorful arc stretching across the sky. However, what if I told you that rainbows are not just arches but complete circles? Yes, circular rainbows are real, though they are rarely seen from the ground. Let’s dive into the science behind this captivating phenomenon.
What is a Circular Rainbow?
A circular rainbow is exactly what it sounds like—a rainbow that forms a full circle in the sky. The reason we typically see only an arc is due to the ground obstructing the bottom half of the circle. To view a full circular rainbow, you need to be at a high vantage point, like an airplane, a tall building, or a mountain.
How To Do Circular Rainbows Form?
The formation of a circular rainbow follows the same principles as a regular rainbow:
- Refraction and Reflection: When sunlight enters a raindrop, it slows down and bends (refraction). The light then reflects off the inside surface of the droplet and exits, bending again. This process separates the light into its constituent colors (dispersion), creating a spectrum of red, orange, yellow, green, blue, indigo, and violet.
- Full Circle Formation: In theory, all rainbows are full circles. The visible part of the rainbow depends on the angle of the sun and the observer’s position. You might see the full circle if you’re high enough and the sun is low in the sky.
- Observation: Circular rainbows are most commonly observed from airplanes because the ground doesn’t obstruct the line of sight. Pilots and passengers sometimes report seeing these complete circles during flights(
FAQ
Can you see a circular rainbow from the ground?
No, from the ground, the horizon typically blocks the bottom half of the rainbow, so we see only an arc.
Why are circular rainbows rare?
They are rare because they require a high vantage point and the right atmospheric conditions to be visible.
What conditions are needed to see a circular rainbow?
You need sunlight, water droplets in the atmosphere, and a high observation point like an airplane or mountain.
Is a circular rainbow different from a regular rainbow?
The process of formation is the same. The only difference is the observer’s perspective, which can reveal the full circle.
Where can you most likely see a circular rainbow?
Circular rainbows are most commonly seen from airplanes, but they can also be observed from high mountains or tall buildings.
