Inferior Mirage Flash
February 04, 2015
On New Year's Day, I decided to photograph the first sunset of 2015 at San Francisco, California. I hoped to see a green flash as the Sun set, and fortunately I wasn't disappointed. An inferior mirage ended with a colorful flash, as shown above. But what's that peculiar wall-like feature stretching across the horizon? It turns out it's also a mirage; an inferior mirage of the cloud bank positioned just above it. Sunlight passing over the water at low angles across the different air layers was refracted in such a way that rays coming from the top of the clouds appeared to be coming upward from the horizon. According to Dr. Andrew Young, turbulence in the convective boundary layer that evening contributed to the observed colors of the flash.
Photo details: Camera Model: Canon PowerShot SX40 HS; Focal Length: 137.0mm; Aperture: ƒ/8.0; Exposure Time: 0.0016 s (1/640); ISO equiv: 100; Software: Adobe Photoshop CS3 Windows.