PITTSBURGH (KDKA) — On a hot day, you may have noticed what looks like water in the distance, when looking down a road.
As you travel down the road, you never reach this deceptive water. You are witnessing what is called a mirage.
The first part of understanding a mirage is understanding that we see things because our brains are processing how the light bounces off of them. That usually occurs in a straight line. The recipe for a mirage, though, changes how that light gets to our eye, thus changing how our brains process the image.
Mirages occur near a hot surface like a road or sand. Near that hot surface, the air is hot and less dense.
The temperature above that hot surface quickly cools off and becomes less dense as you increase elevation. This creates varying densities.
These different densities cause that reflected light to bend, or refract.
For instance, think about when you look out on a hot day, and see a blue sky.
The light bouncing off the blue sky is sent to your eye, telling your brain there is blue sky.
Now, if we create different densities, that light bouncing off the sky is bent toward the ground.
Since our brains perceive light only in straight lines, it is fooled into thinking the light reflection is from something on the ground.
Simply, it makes the bent light look like water!
If there is a taller structure in the distance, its light will also be bent.
This will project that objects image onto the ground, too, further giving the appearance of water.
You can easily bend light at home with an easy experiment. All you need is a clear glass full of water, a piece of paper and a writing utensil.
Draw some arrows on the paper, all in the same direction.
Now, slide that arrow behind the glass and see what happens. You should notice the arrows change direction!
While this is not a mirage, it is an example of bending light.
The glass of water is actually acting as a magnifying glass.
When the light bounces off the paper, the water magnifies it by bending it toward the center to a place called the “focal point”.
Since the light is bent to that point, if you back up a bit, the light continues its path causing the arrow to appear to change direction.
Now you know how to bend light, and now your glass of water just became a little more interesting!