Every day one can see shadows pointing away from the sun, but in rare cases there are also shadows visible in sunward direction. These shadows are projected against the sky. Seeing those spooky phenomena requires a low sun elevation, a high object which seems to tower above the sun, and a transparent “screen” of fog between the observer and the object. In the morning of September 11, 2013, Ulf Köhler observed such a phenomenon on the Hoher Peißenberg (998m). The shadow of the dome of the Mariä Himmelfahrt Pilgrimage Church appeared in passing wafts of mist. When Ulf Köhler changed his position within the shadow of the steeple, the shadow of the dome also changed its appearance. (1–2).
Another article on this topic: “Düsseldorf Leaning Tower and other Shadow Plays”