why mirage is in view when we are far away and not when near?

Answer 1

First of all, what's a mirage? Mirages are not optical illusions, as many people (and Web sites!) think. They are real phenomena of atmospheric optics, caused by strong ray-bending in layers with steep thermal gradients. Because mirages are real physical phenomena, they can be photographed.

Optical illusions, on the other hand, are perceptual quirks of human vision, in which the observer sees something that does not exist physically. Of course, the distorted images produced by mirages may elicit optical illusions, when an observer misinterprets the scene — hence, the confusion of these distinctly different classes of phenomena.

Like Green flashes are colored phenomena due to the dispersion of atmospheric refraction. While every refraction phenomenon has some dispersion connected with it, the dispersion is inappreciable under most circumstances. However, certain mirages produce much larger dispersion effects; and the most spectacular of these are the green flashes. So, to understand green flashes, it is first necessary to understand mirages.

Sometimes people think that the erect image of a classical mirage is “the object itself,” and that the inverted one is “just a mirage,” and somehow not real. But this notion is challenged by 3-image (and other multiple-image) mirages, in which two or more erect images occur: which one, then, do you choose as “the real one”? In fact, all the images are equally genuine; every one of them is as truly “the object itself” as any other, including the inverted ones. And as all the images are in general displaced from the geometric position of the object, location is no indicator of legitimacy.

Answer 2

Mirage is due to total internal reflection requiring angle towards normal being more than the critical angle in the medium(air). That is possible only when u r far . When u r near , the angle w.r.t. normal is less than the critical angle & so, total internal reflection can not take place & no mirage is visible.

Answer 3

Mirage is an optical illusion seen in deserts at summer noon due to which an inverted image of a distant tree is seen formed in the hot sand below it as it is formed in the water.
It is due to the total internal reflection.(for example;
at the summer noon in desert ,the sand becomes hot and the air in its contact becomes very hot and hence rarer.As we move up the air becomes less hot and hence denser. As the rays travel from the tree top to downward,they travel from denser to rarer medium and hence the angle of incidence increases for each lower layer,the ray bends downwards. At a layer when the angle of incidence becomes greater than critical angle total internal reflection takes place. the totally reflected rays are received by an observer far away ,he see an inverted image of the tree formed in sand. This inverted image of the tree produces the impression of reflection from a pool of water..

Answer 4

Mirage is a phenomenon cause by refraction of light from a distance when the refracted rays converge on our eyes.