Anticrepuscular and Crepuscular Rays Above Toronto

July 27, 2010

Photographer: Andrew Yee 
Summary Author: Andrew Yee

What a treat to be able to see anticrepuscular and crepuscular rays in Toronto on two consecutive evenings! In the panorama taken on July 3, 2010 from the western part of Toronto, by the Humber Bay, a pair of anticrepuscular rays stretched over the distant downtown skyline. These frequently unnoticed rays caught my attention about 15 minutes after sunset. They appeared to emerge from the pink band of the Belt of Venus and the blue-gray sky of the Earth's shadow just below it, converging opposite to where the Sun had set.

On the following evening, crepuscular rays were observed to emanate from the horizon in the direction of sunset, as seen from Ward's Island, which is part of the Toronto island chain -- approximately 1.3 miles (2 km) south of the downtown Toronto shoreline (see inset). These rays first came into view about 24 minutes after sunset. The dot of light near the left edge of the image is Venus.

Anticrepuscular and crepuscular rays are shadows that distant clouds cast in the sky. The rays are actually parallel to each other, but viewing perspective gives rise to the appearance that they converge toward the horizon; much like the illusion that railway tracks appear to converge in the distance.

Photo Details: For the panorama -- four overlapping images;, each image taken with the Nikon D90 camera; sigma 17-70mm lens at 24mm (35mm equivalent: 36mm); ISO 640; f/9; 1/25-second exposure time; exposure bias of -1.7EV. For the single image -- Nikon D90 camera; sigma 17-70mm lens at 17mm (35mm equivalent: 26mm); ISO 400; f/8; 1/15-second exposure time; exposure bias of -0.7EV.