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B Can anyone explain this sun reflection in terms of angles?

  1. Oct 18, 2016 #1
    I'm trying to understand the physics of reflection to better draw objects. Normally, you see the reflection of a light source on metallic surfaces where the angle of incidence can equal the angle of reflection. This should reflect an image of the source that is approximately equal in size to how big the source looks from the point of view of the reflection surface, if the surface is non-dispersive. Why is it, then, that the sun stretches across the ocean so far in this pic? I know that water is dispersive, but i don't see how dispersion alone accounts for how far the sun is reflected.

    I'm guessing it's explained by the agitation of the water.

    Last edited: Oct 18, 2016
  2. jcsd
  3. Oct 18, 2016 #2

    In this picture, you can see that the parts of the water facing away from the viewer reflect the sunlight from the position of the viewer up until where the sun would be reflected on unagitated water. Past this point in a direction, the sun is reflected on surfaces facing the viewer. Since surfaces facing away from the viewer are more blocked than those facing towards, more light comes from behind where the sun would be reflected on unagitated water. I believe this is the full explanation, no?
  4. Oct 18, 2016 #3


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    Forget for a moment the bright center lane of the reflection and focus on the edges. What do you see? Does it suggest an answer to your question?

    EDIT: Ah. I see our posts crossed and you are getting it although I think the full picture is simply stated as just an effect of reflections off of an undulating surface.
  5. Oct 18, 2016 #4


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    I'm not sure what you mean by this comment.
    Yes. If the water is perfectly (mirror) flat, there will be just one perfect of the Sun.
    The randomly rippled surface of the water can be looked upon as a whole set of small plane mirrors at random angles; facets, if you like. 'Rays of light' from the Sun will strike all of these elemental mirrors. Rays will be reflected in all directions. Rays from each particular mirror in any particular area of the water will follow the laws of reflection and there will be some of those mirrors which will present a tiny image of the Sun to an observer. Most of the mirrors will send rays in a other directions - presenting images for observers in other directions. Whichever region of water the observer looks, he will see some reflected images in the water but there will be more facets that satisfy the condition for image formation along a line between the horizon just under the Sun and the observer. Paths off that line will produce fewer images and the result is the broad line which tails off on either side. Viewing the water with the Sun over you shoulder, there will be very few facets producing any image at all unless the water is very rough, with almost vertical sides to the waves. Also, the reflection coefficient also reduces considerably as the angle of incidence reduces - the most reflection being for a very oblique angle. (See this wiki link) so the reflection intensity is much higher near the horizon.
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