What is the true shape of a rainbow and why don't we see it?

Rainbows are actually full circles, but we usually only see an arc because the Earth's surface blocks the bottom half. To view a complete circular rainbow, one must be high in the sky, like in an airplane, or use a water spray on a sunny day. These optical illusions are unique due to individual perspectives.

What is the true shape of a rainbow and why don't we see it?
Rainbows are actually full circles, but we usually only see an arc because the Earth's surface blocks the bottom half. To view a complete circular rainbow, one must be high in the sky, like in an airplane, or use a water spray on a sunny day. These optical illusions are unique due to individual perspectives.