Why Sunset Reflections on Water Smear Vertically

Everyone has seen sunsets and/or sunrises over water such as a lake or an ocean. We have all noticed that the fact that the water is not perfectly smooth causes the reflection of the sun to smear. And, I’m sure that most of us have noticed that the smear is always vertical. The natural question to ask is: why vertical? In this paper, we will show that the size of the angular smear in the vertical directionis larger than in the horizontal direction by a factor of 1/θ, where θ is the angular height of the sun above the horizon measured in radians.