Recently I led a photography workshop in Italian Dolomites with Marc Muench from Muench Workshops. One of the evenings we were treated with most beautiful conditions one can imagine, heavy storm with dark clouds, followed by a rainbow, anticrepuscular rays and amazing sunset colours.
At one point we noticed beautiful god rays coming from behind the mountain. Normally I would say these are sun rays, but the sun was setting behind our backs. So what were these rays if not from sun?
It turns out this phenomena is called Anticrepuscular Rays – the opposite of Crepuscular rays (more commonly known as god rays or sun rays and come directly from sun) and they appear on the opposite side of the sky from sun.
Anticrepuscular rays are usually visible at sunrise or sunset. This is when light backscattering is larger (due to low angle of to the horizon). Anticrepuscular rays are weaker than crepuscular rays because backscattering is less than forward scattering. These rays are essentially parallel but they seem to converge to a vanishing point due to optical illusion from linear perspective.
The only other time I witnessed this phenomena was three years ago, in Dolomites as well. It seems I need to go there more often – high mountains are ideal for unusual weather.
Have you ever witnessed these rays yourself? Where?