Month: September 2015

Mirages: Not Incorrect Views of Reality, Just Different

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Commonly associated with nature, mirages are visual illusions where what we see is correct, but abnormal. Mirages in nature are most commonly caused by unusual bending of light under unusual air conditions. The view can be so abnormal that the viewer ‘can’t believe his eyes.’

The most famous mirage is when it erroneously appears as if a pool of water is in the desert. More than a few thirsty wanderers have found nothing but disappointment ahead. The above pictured water in the road is the same type of mirage. Another related mirage is when sailors see an upside down ship in the sky. Enough to convince a pirate to swear off the hooch

These three particular mirages happen when there are abnormal layers of hot versus cold air that cause the light to refract, or bend, from its usual course. This bending causes an object to appear in an unexpected place. In the desert and highway a piece of the blue sky appears below the horizon, and is wrongly interpreted to be water. At sea a ship is bent upwards so it appears to be in the sky air.

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A mirage is called a superior mirage where the object appears above where it normally appears (boat in sky). An inferior mirage is when the object appears below the where it normally appears (sky in desert).

The inferior mirage happens when there is hot air near the ground. It shouldn’t surprise that inferior images commonly happen when the ground surface is hot (desert, summer highway).

A superior mirage happens when there is cold air near the surface. They commonly appear in the arctic and over frozen water.

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Sunrise mirage. One of the most striking superior mirages is a sunrise mirage. These are seen over frigid areas, such as frozen lakes and seas. The light of the sun is bent upwards along the earth’s curved surface making the sunrise appear earlier than normal. The sun is also distorted. Sometimes two suns are seen at once, one superimposed over the other.

sunrise mirage over a frozen Minnesota lake

sunrise mirage over a frozen Minnesota lake

This mirage was noticed centuries ago by Western explorers stranded in the arctic over the winter. That far north there is no sun 24 hours a day for much of the winter. The explorers were surprised when the first sunrise of the season appeared days before it was supposed to. It wasn’t until centuries later that experts realized the explorers had witnessed this mirage.

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Water can bend light just as air can, the light bending from air to water or water to air (or air to water to air, etc). A hardboiled egg distorts from normal appearance in a glass of water. The experienced spear fisher knows to spear to the side of the image of the fish or he will miss. Stones appear to ripple and wave in a crystal clear brook. One can study and demonstrate how mirages work with a drinking glass.

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The mirages aren’t wrong views of an object, just different. Our normal vision involves distortions, including to color, details and angles, so one can hardly claim our normal vision is perfect and anything different imperfect. When they wish a better look, people with 20/20 vision intentionally distort their vision with magnifying glasses, binoculars, periscopes, video cameras and sunglasses.

Sailor looking through a submarine periscope

Sailor looking through a submarine periscope

When you view a bird through binoculars the lens distorts the light to make the bird appear larger and more detailed. You don’t consider the binocular view of the bird wrong. You consider it to be more reliable than your naked eye view (“I thought it was a hawk, but it’s just a crow.”) A submarine’s periscope bends light via mirrors so a sailor can see above water. The sailor doesn’t consider the view make believe. He considers it a view of reality.

Humans classify views as mirages when they are abnormal and mysterious (at least to the viewer). There are many brilliant atmospheric effects that aren’t considered mirages, as they are well understood. Little is more magnificent than a rainbow, but they are frequent and people know there is a scientific explanation. Fog, snow, sunsets and seeing our reflection in puddles would be considered astounding if they weren’t common events.

That thousands of pounds of bright white snow changed into grass in one (hot) weekend doesn’t cause you to write to Ripley’s Believe It Or Not. You are well aware heat melts snow and underneath the snow is grass. You mowed that grass a few months ago. Ripley himself likely had this occur on his lawn numerous times. The changing of the season is impressive, but only a mirage to folks who have no memory of it.

After waking up in the morning and seeing the season’s first blanket of snow, my very young sister turned to my dad and said, “Daddy, how’d you do that?”

When people move to new geographies they often experience new weather phenomena. When I moved to Seattle, I experienced unusual (to me) night lighting effects caused by Puget Sound and clouds. One night I thought there was a large fire on the other side of the sound. I later found out it was the lights of a distant hill-hidden town reflecting off of low clouds. This created a low, fiery glow. I see this lighting and it no longer fazes me. The first time I saw it, it was a mirage. Now it’s town light reflecting off of low clouds.

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You can’t trust water. Even a straight stick turns crooked in it.” — W.C. Fields

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