River in the Sky

Captured by Matthew Shepherd at Troy, New York. The wavy orange line is an image of the nearby Mohawk River projected by a low sun onto the underside of the clouds.

All images ©Matthew Shepherd, shown with permission

Calm water on the river reflects parallel sun rays back upwards. They impinge on the cloud underside to form an image of the river.

The upward going sun rays are visible in the lower image.

Arctic dwellers and explorers used to use a similar effect, an "Ice Blink". Distant leads, clear water separating ice floes, were imaged onto the undersides of clouds near the horizon.

About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed
The sun was 5.5° high and the illuminated cloud patches 6-10° above the horizon. The distances of the reflecting parts of the river are less easy to judge but 7-15km likely brackets them. That gives a cloud underside height of very approximately 4-9000 ft. Not unrealistic for low level clouds.