Castles in the Sky

by Roving Ranger in Borrego

There is a legend from the King Arthur Stories, of a great sorceress apprentice. Her name was Morgan le Fay, and she studied under Merlin the Magician! Her talent was her ability to draw castles in the sky, which lured attacking ships and their sailors to their doom. While we do not suffer the same fate as those poor sailors of old, we do still today honor her talents in the form of the wonderful Fata Morgana Mirage! 

Photo by Steve Bier

What is a Fata Morgana Mirage, you ask? Put simply, this type of mirage is a mixture of mirror images of an object (like a tree, a train, a truck, a mountain, etc.) “projected” above the horizon. This image is an object inverted, reversed, and standing on its sides. 

Photo by Steve Bier

The confusion you experience is in the way your eye perceives the light coming into it from a long distance. The light itself is being refracted, or bent, by different layers of cold and warm air as it passes through the atmosphere. Have you ever taken a straight stick and placed it into a pool or bucket of water? The light passing through the water is refracted, causing your eye to perceive the straight stick as bent. A similar thing is happening in our atmosphere. Different layers of air temperature affect the light passing through it. Warm air tends to bend the light.

We see this in summer on a hot asphalt roadway when warm air at ground level is overlaid by cooler air. Light rays passing through the warm air bend back toward the sky and we see a mirage (mirror image) of the reflected sky that appears as a pool of water on the ground. This is known as an inferior mirage.

Photo by Steve Bier

The opposite effect, known as a superior mirage, occurs when the warm air is above a layer of cold air. Light passing through the atmosphere bends in the warm air, which your eye perceives as a projected image skyward. This type of mirage can often be seen as you travel the long stretch of highway 78 towards the Salton Sea. Trees that line the highway 86 corridor can often be seen suspended above the highway, with the inverted image of vehicles traveling by. 

The Fata Morgana is a more complex version of the superior mirage with several refracted “mirror images” combining in the sky.  A great place to witness Fata Morgana Mirages is out near Rango Way and Borrego Valley Road. Get up early in the winter morning (near to or just after sunrise) and head out toward Borrego Springs Road and Rango Way. As Borrego Springs Road turns south to become Yaqui Pass and Rango Way, pull off the road and look to the east toward the Borrego Mountains. You will very quickly make out atmospheric “distortions” of the West Butte as portions of the mountain top begin to change before your eyes.  Keep your eyes on the Borrego Mountain Wash in the foreground and you will likely see the image of some of the sand dunes stretched, compressed and elevated along the side of West Butte. The flatter the terrain, the better the effect. In the earlier image of Highway 78, the floating mountain in the background shows Picacho Peak and Indian Pass suspended and inverted in air, like a Castle in the sky. 

Photo by Steve Bier

 

To learn more about Mirages and other atmospheric phenomena check out these links...
http://mintaka.sdsu.edu/GF/mirages/mirintro.html
www.Spaceweather.com