why should you see a mirage as a flowing water?
Answers
A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.
During a hot summer day, air just above the road is very hot and the air at higher altitudes is cool.
It means that the temperature decreases with height. As a result the density of air increases with height.
We know that the refractive index of air increases with density. Thus the refractive index of air increases with height.
So the cooler air at the top has greater refractive index than the hotter air just above the road.
Light travels faster through the thinner hot air than through the denser cool air above it.
When light from a tree passes through a medium just above the road, whose refractive index decreases towards the ground, it suffers, refraction and takes a curved path because of total internal reflection.
This appears to the observer as if the ray is reflected from the ground. Hence we feel the illusion of water being present on the road.
The inverted virtual image of the tree is seen by the observer. This is a mirage.
Mirage a virtual image that forms as a result of refraction and total internal reflection in Earth's atmosphere Many people have noticed what appears to be a pool of water infront of them as they drive along a highway. This pool of water seems to be only a short distance away, yet the car never seems to reach it. The pool appears to be constantly moving away. The pool of water on a highway is a mirage. A mirage can appear when light is travelling from cool air into warm air. The index of refraction for air decreases as the air gets warmer. This results in light bending farther away from the normal as the air temperature continues to increase. Eventually, total internal reflection occurs in the lowest (hottest) air layer. The light ray now travels up from the hottest layer to the cooler layer above and is gradually refracted toward the normal as the air temperature decreases. This light ray eventually enters your eyes. A motorist who sees this curved light forms a virtual image on the highway. In reality, the pool of water is a virtual image of the sky on the highway. Because the human brain perceives light to travel in a straight line, the motorist projects the image of the sky onto the highway
JB