Is it unique to see a low-arch rainbow?
I’ve had lots of rainbow photos sent my way including a photo from Tim Gallant.
The photo also came with a question: “Is it unique to have a rainbow (with) this low of an arch and if the cloud above was too heavy for the rainbow to have a higher arch and why?”
Let’s remember how rainbows form. Light from the sun enters water droplets, slows down, bending it and changing its direction. This process is known as refraction. The colours in the visible light spectrum are separated and reflected out of the droplet, making up the colours we see in a rainbow. So, the cloud is not weighing down the rainbow.
The main factor that determines how much of a rainbow arch is visible on the horizon is the position of the sun in our sky. The higher the sun is in the sky, the smaller the arch of the rainbow is visible above the horizon.
This is why you often won’t see rainbows in the middle of the day, and why you’re more likely to see them during the morning or late afternoon/evening, depending on the time of year. Given the arch of this rainbow is low on the horizon, it likely formed in the early afternoon and is certainly unique.
While this rainbow would look very similar if we were all standing with Tim to view it, each person has a different antisolar point and view of the horizon, so technically no one sees the same rainbow. Interesting, isn’t it?
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