|Chicago Seen Floating Above Lake Michigan|
Joshua Super and Shalee Blackmer were camping at Michigan’s Warren Dunes State Park when they noticed strange rectangular figures over the horizon of Lake Michigan.
Turns out tt was the city of Chicago, some 50 miles away.
The bizarre effect was the product of a special atmospheric condition called a “superior mirage.”
A superior mirage occurs when an image of an object appears above the actual object, dueto the refraction or bending of light waves from the object down toward the eyes of the observer. Downward refraction occurs because air closer to the ground is colder, and therefore more dense, than air higher up.
Superior mirages can take the form of looming, towering, and inversion, depending on the particular density structure of the air column.
In looming, distant objects appear to float above the horizon, and objects that are below the horizon may come in to view. In towering, rays from the upper portion of an object are bent more than those from the lower portion. This results in the object appearing to be stretched as well as elevated.
In a superior mirage with an inverted image, the gradient in atmospheric density is so sharp that rays from the lower portion of an object are bent considerably more than rays from the upper portion of an object, causing a mirage of the object to appear inverted above the object. The object appears as it normally would at the same time, because some light continues to travel to the eye directly from the object
Sometimes an object below the horizon may even become visible. In this case, the optical ray curvature was stronger than the curvature of Lake Michigan’s surface, which made it possible for Super and Blackmer to see the city’s buildings—even from across the Great Lake.