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Thread: Heat Wave Shadow

  1. #1 Heat Wave Shadow 
    Time Lord zinjanthropos's Avatar
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    Exactly whatís going on when I can see heat wave shadows but not the wave itself? Itís early a.m. here and Iím sitting watching these shadows dance on my porch floor, yet I canít see the actual waves/air causing them.


    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    Bullshit Intolerant PhDemon's Avatar
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    When air masses of different temperatures come together you get turbulent mixing, this means you have constantly moving streams of gas at different (and changing) temperatures. Gases at different temperatures have different refractive indicies and bend any light rays passing through them by different amounts. The shadows you observe are due to the interference of these light rays.


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    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by PhDemon View Post
    When air masses of different temperatures come together you get turbulent mixing, this means you have constantly moving streams of gas at different (and changing) temperatures. Gases at different temperatures have different refractive indicies and bend any light rays passing through them by different amounts. The shadows you observe are due to the interference of these light rays.
    Thanks PhD, now that the sun is higher in the sky there are no wave patterns on the floor. So these patterns are not shadows but only dark areas caused by interfering light waves, like the bands observed in a double slit experiment? I mean air doesn’t actually blot out the sun, does it?
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    Bullshit Intolerant PhDemon's Avatar
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    The air doesn't blot out the sun, the passage of light through regions of air with constantly changing refractive indexes sets up a constantly changing interference pattern which you see as a series of moving shadows and brighter regions. This effect is most pronounced when the air in which the temperature is rapidly changing is between your eye and the sun (I.e. dawn and dusk), when the sun is overhead the light is not passing through the air directly to your eyes.
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  6. #5  
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    Quote Originally Posted by zinjanthropos View Post
    Exactly what’s going on when I can see heat wave shadows but not the wave itself? It’s early a.m. here and I’m sitting watching these shadows dance on my porch floor, yet I can’t see the actual waves/air causing them.
    Nice question zinj.You are the questioner in chief

    (good answers too)
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  7. #6  
    Time Lord zinjanthropos's Avatar
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    Quote Originally Posted by geordief View Post
    Quote Originally Posted by zinjanthropos View Post
    Exactly what’s going on when I can see heat wave shadows but not the wave itself? It’s early a.m. here and I’m sitting watching these shadows dance on my porch floor, yet I can’t see the actual waves/air causing them.
    Nice question zinj.You are the questioner in chief

    (good answers too)
    Just trying to make sense of the world around me. Don’t know if I’ve been able to word one right yet, probably the most difficult thing to do, with science folks reading them. Lack the correct terminology many times.

    Guys here do their best to answer and I appreciate it. They’re comfortable and confident when they answer. Like heat waves, there’s a scientific explanation for almost everything.

    When PhD was talking interference patterns I thought of zebra markings. Perhaps somehow evolution has picked up on heat wave interference patterns and incorporated them into a most bizarre camouflage protection. Maybe that is a question for biologists. Great how an answer in one field can generate a thought about something elsewhere. It’s all connected geo, everything....JMHO
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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  8. #7  
    exchemist
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    Quote Originally Posted by zinjanthropos View Post
    Quote Originally Posted by PhDemon View Post
    When air masses of different temperatures come together you get turbulent mixing, this means you have constantly moving streams of gas at different (and changing) temperatures. Gases at different temperatures have different refractive indicies and bend any light rays passing through them by different amounts. The shadows you observe are due to the interference of these light rays.
    Thanks PhD, now that the sun is higher in the sky there are no wave patterns on the floor. So these patterns are not shadows but only dark areas caused by interfering light waves, like the bands observed in a double slit experiment? I mean air doesn’t actually blot out the sun, does it?
    What you have is lensing, in which the "lens" is constantly fluctuating.

    At any given moment, some light is bent and concentrated in one area, while another becomes slightly deprived of illumination in consequence, due to some of the light being bent away from it. You get just the same sort of thing on the bottom of an outdoor swimming pool when there are ripples on the surface of the water, but more pronounced of course.

    You expect it more when the sun shines obliquely through a column of warming air, in which there are denser and less dense pockets within it at different heights above the ground. When the sun shines down near-vertically through such a column, you don't get the effect so much.
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