|Dawn Cloud Shadows - by Nancy Shelton of Medina, Ohio February 2009. ©Nancy Shelton, shown with permission.
The shadows are cast by clouds on or beyond the eastern horizon.
Shadows can be two-dimensional, those cast on surfaces, or three dimensional. These are a mixture of both - 3D pipes of dark air extending across the sky and 2D shadows where the pipes intersect clouds.
Rays from the 93 million mile distant sun are essentially parallel as they pass through our atmosphere and the shadow pipes are parallel too. Perspective makes them appear to diverge.
The parts higher in the sky are closest to us, subtend a larger angle and appear largest.
Man-made clouds also cast their shadows through the air as do mountains and the Earth itself.
Visit the OpticsPOD Rays & Shadows gallery for more.