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Floating land, wall of water appear over Chesapeake Bay amid rare mirage

The unusual display is known as the ‘Fata Morgana’

The Fata Morgana appears over the Chesapeake Bay on Thursday. (Twitter @RobbMDWx)

If you were standing on the banks of the Chesapeake Bay and spotted a 100-foot-high vertical wall of water, odds are you would have been perplexed if not frightened.

Now imagine that distant tsunami-like tidal wave was flanked by pillar-like cliffs you had never seen before.

That’s exactly what appeared Thursday when Robbie, a local high school student and Capital Weather Gang reader, trained his camera’s viewfinder across the bay.

That’s the Chicago skyline, but these photos were taken from Michigan

Robbie, who preferred not to provide his last name, maintains the Twitter account @RobbMDWxMedia, where he posts “astrophotography, storm chases, winter weather coverage and more.”

What he captured isn’t edited, nor is it the result of a sci-fi fantasy. Instead, his image captures a rare phenomenon known as the “Fata Morgana,” a sight coveted by mariners and meteorologists alike for its curious, devilish bending of light.

The Fata Morgana is a mirage. Mirages are weather-induced distortions of reality. Sometimes, they take the form of apparent bodies of water that aren’t really there. More frequently, mirages are perversions of the truth, appearing as floating objects, sometimes upside-down, vertical stretches of distant apparitions or the blurring of the horizon. On occasion, multiple effects may be present simultaneously.

In the case of Thursday’s episode, Robbie’s photos show an unaffected foreground, including a cone atop a buoy or anchored channel marker, juxtaposed against a vertically dilated horizon. Instead of a crisp, clean line, the horizon has instead been stretched upward and downward, giving the appearance of a jagged wall of water, adorned with overlooking cliffs, rising like a delicate yet threatening comb out of the bay.

The Fata Morgana is a special type of superior mirage, a term assigned to mirages that are manifest in objects appearing taller or higher than they actually are.

Based solely on the images, we’re able to make several conclusions about the weather present at the time the photographs were taken.

Heard the inauguration fireworks far from D.C.? Blame a temperature inversion.

First, we know that the ocean was significantly cooler than the ambient air temperature — enough so as to induce an inversion. An inversion marks an increase in air temperature with height; ordinarily, air temperature decreases with height. Instead, water temperatures in the lower to mid-40s cooled the air upon immediate contact with it into the 50s; just above this shallow layer, temperatures in the 60s or perhaps near 70 were probably present.

Washington hit 79 degrees on Thursday, nearly 25 degrees above average, setting a record for the date.

The specific temperature profile is key, since the air’s temperature determines its index of refraction. Refraction describes the bending of electromagnetic waves, including light and radio waves. Since the air’s index of refraction changed so dramatically in the lowest levels of the atmosphere, light that would otherwise rise was instead refracted back toward the ground. That’s known as a ducting effect. That ducting bent the light to follow the curvature of the Earth, allowing the observer, Robbie, to witness objects stretched to the top of the inversion.

The same set of circumstances is also beneficial for radio wave propagation, since signals are amplified at greater distances near the surface.

The Fata Morgana made headlines two weeks ago, when a floating ship was photographed offshore of Cornwall, England. The episode was unusually crisp, the mind-boggling photograph going viral on social media. Many originally questioned its legitimacy, but meteorologists quickly confirmed that the photograph was, in fact, legitimate.

Some of the most visually striking mirages in the world reliably form over the Salar de Uyuni, or the world’s largest salt flats, in Uyuni, Bolivia. During the dry season, complex mirages form because of bizarre temperature profiles. The vast, white ground is comparatively cool since it reflects sunlight, but air just a few meters above the ground may hover between 80 and 90 degrees.

That allows for spectacular scenes made up of monster trucks, giant people, floating mountains and clouds dipping into the horizon.