In hot deserts , we generally ten to see mirages . Why do we see these mirages and what causes it . If possible draw a ray diagram

Asked by raghavdinesh | 1st Mar, 2015, 08:15: AM

Expert Answer:

Mirage is an optical illusion caused by the atmospheric refraction. On hot days travellers on a tarred road or in deserts get the impression of pools of water on the road. This is called mirage.
Sunrays heat the air near the road. This hot air is rarer and the air just above this hot layer is cool and its density is greater. So the sunrays travelling towards the road are gradually refracted away from the normal, because they travel from a denser medium to a raer medium. When the angle of incidence is greater than the critical angle the ray gets totally reflected. Thus the sun rays, reflected upward, reaches the observer. For the observer this light seems to have been reflected from the road and gives the appearance of a shining lake. 

Answered by Jyothi Nair | 1st Mar, 2015, 05:53: PM

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