Subsun Observed from Grand Targhee Ski Area, Wyoming

Photographer: Glenn McCreery  
Summary Author: Glenn McCreery 

I observed this very bright subsun (seen at lower left) from a chairlift at Grand Targhee Ski Area, Wyoming, on a very cold, but brightly sunlit and windless, winter’s day. Subsuns occur when the Sun reflects off the flat upper surfaces of airborne, plate-shaped ice crystals. But you need to be looking down to see them, not up. The average angle of a subsun below the observer’s horizontal plane is the same as the Sun’s angle above the horizontal plane. Therefore, subsuns are only seen when the observer is at some altitude above the surface and looking down, most commonly from an airplane. It’s quite rare to see a subsun at such a close distance that reflections from individual ice crystals may be discerned.

A portion of a faint ice halo may be seen in the upper right of the photograph. The “flying saucer” looking object in the lower right-hand corner is due to internal reflections of the Sun in the camera’s lens. Photo taken on December 9, 2018.

Photo details: Olympus TG4 camera; 1/500 second exposure; f:8.0; ISO 100, 24 mm (35 mm equivalent).



Grand Targhee Ski Area, Wyoming Coordinates: 43.79, 110.96

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Brilliant Subsun