Lake Superior Mirage
April 08, 2011
The photo above appears to show a space-ship like object hovering above the sea. It's actually an inferior mirage of a lake freighter on Lake Superior. These immense ships are sometimes over 1,000 ft (300 m) long. This one is likely 16 mi (26 km) distant, which is the approximate distance from shore to the shipping lanes. I took the picture from Two Harbors, Minnesota on October 21, 2010 with the camera facing east. The air temperature at the time (7:20 a.m.) was about 35 degrees F (2 C), and the water temperature was perhaps 20 degrees F (11 C) warmer. A layer of cooler air was trapped between the lake water and warmer air just above creating a temperature inversion.
With an inferior mirage, an object looks lower than its true position -- the index of refraction decreases rapidly toward the surface. Light refracts toward the more dense medium. Note that the horizon looks to be rather rough. This looming (of waves) is a signature of mirages.
Photo Details: Camera Maker: NIKON CORPORATION; Camera Model: NIKON D80; Lens: 70.0-300.0 mm f/4.0-5.6; Focal Length: 300.0mm (35mm equivalent: 450mm); Focus Distance: 4294967295.00m; Aperture: f/5.6; Exposure Time: 0.0008 s (1/1250); ISO equiv: 200; Exposure Bias: none; Metering Mode: Matrix; Exposure: program (Auto); White Balance: Auto; Light Source: Unknown; Flash Fired: No; Orientation: Normal.