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| Shadow Hiding Michael Grossman took these images half an hour before sunset. His perspective distorted shadow slants across the field. Brocken spectre shadows are similarly distorted. His head (or rather where the camera shadow would be if we could see it) seems to be surrounded by a bright glow - the 'opposition effect'. Elsewhere, long shadows, actually parallel, appear to point toward the glow. All images ©Michael Grossman, shown with permission |
| The 'glow' is the absence of shadows. When looking directly away from the sun, towards the antisolar point ASP, the shadow of a tree or clump of soil is hidden behind the object. Look away from the ASP and shadows hide less and less. The effect occurs because the landscape is lit by parallel light while the eye looks at a whole range of angles. |
Not all glows opposite the sun are shadow hiding. Retro-reflection and backscattering by rocks play a role. Dew wetted fields have a heiligenschein. |
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| In direction 'a' - along the sun rays - the shadow is hidden by the tree. That area appears bright because no shadows darken it. The shadow of the trees at 'b' and 'c' appear towards the antisolar point. They are visible and reduce the area's average brightness. |
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| Michael had to jump in the air to get this one. |
The view from the eye. |