Cloud Mirage at Sunset Above San Francisco, California
January 08, 2013
Photographer: Mila Zinkova; Mila’s Web site
Summary Author: Mila Zinkova; Jim Foster
The photo above showing a marbled strip of sky just above
the western horizon offshore San Francisco, California, is actually a mirage.
We’re used to seeing objects like ships and distant mountains miraged but when
clouds or marine layers (cloud banks) are distorted they often escape notice. The
mirage mechanism is, of course, the same: variations in air temperature and density at the air/water boundary and the layer just above it. However, in this case the entire horizon was
distorted as the Sun was setting. Sunny, warm weather on this November day
favored the development of a superior mirage caused by relatively warm air
overlying a much cooler surface air layer. On their way to the observer, the
nearly horizontal rays of sunlight were bent downward during their passage
through the warmer air layer. Thus, the refracted image of the distant marine
layer appears stretched above its actual position. Photo taken in late November
2012.
Photo details: Camera Maker: Canon; Camera Model: Canon PowerShot SX40 HS; Focal Length: 150.5mm; Aperture: f/5.8; Exposure Time: 0.0050 s (1/200); ISO equiv: 500; Software: Adobe Photoshop CS3 Windows.