Sometimes on hot summer days the road appears to be wet as shown in Figure P24.104. The black surface becomes very hot, heating up the air just above the road. This increase in temperature decreases the density of the air and in turn decreases its index of refraction. The result is that light from a distant object can be totally internally reflected from the layer of air just above the surface of the road, producing a mirage.
(a) If your eye level while driving your car is 2.0 m above the surface of the road and you observe a mirage 100 m ahead, what is the index of refraction of air just above the ground?
(b) Describe how you might use a mirage to estimate the temperature of the air just above the ground.