Why do shadows “pinch” together and form a bridge when they get close enough to each other?

Question

Why do shadows “pinch” together and form a bridge when they get close enough to each other?

In: 13

Answer 1

Are these fuzzy shadows produced by multiple non-point lights? If so, what you’re seeing is the removed light from both shadows stacking up. If one shadow removes half the direct light from one source, and the other shadow removes half the direct light from another source, that’s similarly dark to each shadow removing the full illumination from one source.

Answer 2

Because the sun isn’t a single point of light. Since the sun produces a diffused source of light, shadows cast have a feature called a penundra. Another reply refers to this as a “fuzzy shadow.” What you see are the penundras of two different shadows landing on top of each other.