Crepuscular Rays in the Philippines and Rainbow Wheel Over Belgium

March 11, 2022




Photographers: Joaquinna Reigne P. Barbosa (top); Thierry Lombry (bottom)

Summary Author: Joaquinna Reigne P. Barbosa; Thierry Lombry; Cadan Cummings

The top photo features crepuscular rays visible behind clouds at sunset on Boracay Island, Philippines. Crepuscular Rays, also known as “God rays”, are sunbeams that usually appear during sunrise or sunset. The rays form when the Sun passes behind a cloud or landform on the horizon, and a portion of the light shines between the gaps. These sunbeams are emphasized when there is dust, smoke, and other small particles in the atmosphere due to increased Rayleigh scattering of incoming sunlight. This photo was taken on July 1, 2021.

In contrast, the bottom photo taken near Namur, Belgium on March 30, 2018 shows sunbeams emanating from the horizon near a rainbow. Atmospheric optics events can either originate from the horizon near the Sun or at the antisolar point opposite the Sun. Since rainbows always arise at the point in the sky directly opposite the Sun, these sunbeams are an excellent example of anti-crepuscular rays often called a rainbow wheel. The phenomenon was named because the rays appear like spokes of a wheel formed with the primary and secondary rainbows. Both the crepuscular and anti-crepuscular rays in the images above appear to diverge from the horizon due to perspective.