UHP beam in the rain 2

Here's a closer look at the light beam in the rain, viewed from the side with the light going from left to right. The zone of total internal reflection can be clearly seen on the left. This zone is bordered by messy rainbows which arises from the wavelength-dependent refraction of light in the droplets. This colored effect is not as clean as in proper rainbows because of a great variability in the shape and size of the water drops and the very short viewing distance.