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Why does heat reflect sunlight? (ie: mirages)

  1. Aug 23, 2011 #1

    baywax

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    The title of this thread is all I have to ask about this. You've seen mirages, if they are caused by light reflecting off heat I am wondering why this takes place. Thank you.
     
  2. jcsd
  3. Aug 23, 2011 #2

    cepheid

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    Heat causes air to rise which causes a gradient (a progression) in the density of air with height. This causes a gradient in the refractive index of the air, and that (the change in refractive index) bends the light.
     
  4. Aug 24, 2011 #3
    Usually in hot desert, because of the hotness of the sand the density of the air which is close to it decreases and as we go higher/upper the density of air relatively increases so we can imagine them as layers.(as the pic has shown)
    mirage.jpe totint.gif
    As we know that light changes its direction and speed when it travels from one dense medium to another dense medium, when this bend exceed the critical angel, it starts following the laws of reflection . . . and the reflection bends again and reaches to our eye . . . and thn we call it MIRAGE
     
  5. Aug 24, 2011 #4

    baywax

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    Ah, thank you! I realized after posting that it was the air rather than the heat doing the reflecting. Thanks again!
     
  6. Aug 24, 2011 #5
    I hate to be a stickler, but heat doesn't reflect sunlight; it refracts it. The air bends the light ray's path. Both sadaf2605 and cepheid are completely correct with their explanations. I just thought I point out that triviality.
     
  7. Aug 26, 2011 #6

    baywax

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    My mistake, refracts. Thank you.
     
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