Opposition effect streak

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On a December '02 afternoon an 8º high sun cast long sharp shadows over a field of barley stubble, the remnants of harvesting. A bright streak appears to slant upward at 11 o' clock from the shadow of my head (actually from that of the camera which marks the antisolar point). The effect was subtle and more easily seen while walking.

This is an opposition effect "streak". The stubble approximates to an array of parallel cylinders. When looking to the right or left of the antisolar point their shadows are no longer hid and the field therefore looks darker. But when looking up or down, the cylinders still hide their own shadows (close-up view) and so generate the bright streak.   Image©Les Cowley