Sky-wide rays

View larger. | Where crepuscular rays meet anti-crepuscular rays. Photo by Ken Christison.

Ken Christison caught this wonderful photo on August 5, 2018, and he asked:

Are crepuscular rays called that when they go from horizon to horizon? I know they are crepuscular when they emanate from the sun and anti-crepuscular where they terminate in the opposite direction. I caught this with my moderate fisheye lens from northeastern North Carolina.

Ken, for questions like these, we go to a true expert, Les Cowley of the website Atmospheric Optics. Les doesn’t call them by any special name, other than sky-wide rays. He explained that images like yours show:

… brilliantly that familiar crepuscular rays and the less well known anti-crepuscular rays are really the same objects.

And he said that:

The rays are all parallel to each other, real columns of sunlit and shadowed air. In the west, perspective effects make them appear to converge towards the sun as they get more distant. They again appear to converge in the east, this time towards the antisolar point. The rays in the antisolar direction, are called anti-crepuscular.

Thank you, Ken and Les!

Bottom line: An August 2018 photo showing where crepuscular rays meet anti-crepuscular rays.

from EarthSky https://ift.tt/2AUuGOP

View larger. | Where crepuscular rays meet anti-crepuscular rays. Photo by Ken Christison.

Ken Christison caught this wonderful photo on August 5, 2018, and he asked:

Are crepuscular rays called that when they go from horizon to horizon? I know they are crepuscular when they emanate from the sun and anti-crepuscular where they terminate in the opposite direction. I caught this with my moderate fisheye lens from northeastern North Carolina.

Ken, for questions like these, we go to a true expert, Les Cowley of the website Atmospheric Optics. Les doesn’t call them by any special name, other than sky-wide rays. He explained that images like yours show:

… brilliantly that familiar crepuscular rays and the less well known anti-crepuscular rays are really the same objects.

And he said that:

The rays are all parallel to each other, real columns of sunlit and shadowed air. In the west, perspective effects make them appear to converge towards the sun as they get more distant. They again appear to converge in the east, this time towards the antisolar point. The rays in the antisolar direction, are called anti-crepuscular.

Thank you, Ken and Les!

Bottom line: An August 2018 photo showing where crepuscular rays meet anti-crepuscular rays.

from EarthSky https://ift.tt/2AUuGOP