File:Heiligenschein near Foxholes Farm - geograph.org.uk - 1122736.jpg

English: Heiligenschein near Foxholes Farm This is a view of the photographers shadow looking north at mid-day in the valley just east of Foxholes farm. The shadow of the photographer is surrounded by a distinct glow from the sun which is directly behind him and low in the sky.

The bright region surrounding the shadow an observer's head casts on a irregular surface is called Heiligenschein (German for Holy Glow).

It is most often seen when the sun is low in the sky and when the shadowed surface has dew on it, although it can be seen on dry irregular surfaces. This grass was irregular and damp. The cause of the heiligenschein is different depending upon whether it is seen over a dry or a dew- covered surface. When an observer's shadow is cast on a dry, irregular surface (such as grass or stones), each of the irregularities near the antisolar point(close to the observers shadow) covers its own shadow and so the observer only sees the bright image. Away from the anti-solar point the returning light is a mixture of light and shadow and the net light returned is less. When the sun is low in the sky, the long shadows result in larger shadows away from the solar point and so the contrast with the brighter region near the antisolar point is greater. While this effect can be found on any irregular surface it is enhanced by the presence of dew. Dewdrops on the surface of the leaves focus sunlight on the leaf where it is reflected back diffusely. The drop, acting as a lens , collects a large fraction of this diffusely reflected light and refracts and reflects it back to the obsever instead of being diffused. Heiligenschein is sometimes called Cellini's halo, after Benvenuto Cellini who described it in the 16thC. He thought it indicated God's benevolence towards Him!