When sunbeams reflect off a smooth lake or sea, they radiate upward. The perspective lines of the parallel rays appear to vanish a point well below the horizon, but actually the sun still hasn’t set.
These reflected sunbeams, or "inverted crepuscular rays", occur often toward the end of the day, not long before sunset. The rays show up best when there’s a dark band of clouds behind them.
During his sketching sojourn to Jamaica, Frederic Church captured the effect in this plein air painting.
More on Frederic Church in Jamaica
More on sunbeams in Color and Light: A Guide for the Realist Painter