Crepuscular rays

Pencil of rays or light tufts are a phenomenon of atmospheric optics, which is caused by the occlusion of the sun by atmospheric haze. In most cases, this phenomenon is observed in clouds, which is why we also speak of clouds rays. In a very deep sun's position, the effect can also extend over the entire sky, with one speaks then of crepuscular rays. These should not be confused with light pillars. If you have the sun at your back, so you can then see the Anti-Crepuscular rays at the antisolar point under favorable circumstances.

Mode of origin

The direct solar radiation is blocked by the clouds and seems to come at their edges to the fore. Water and dust particles in the air - the aerosols - spread these beams at a small angle and thereby steer this in the eye of the observer. The rays stand out from this cloud shadows from and occur only visible thus produced what is known as the Tyndall effect.

The same effect shows up as a movie projector, which makes the dust particles visible in a room, or even from car headlights when driving through fog. He shows, therefore, especially when the sun is low, because the aerosol concentration is highest, and the brightness contrasts occur at dawn most apparent.

Due to the effect of converging lines is actually assumes the parallel rays of the sun distorts true. It appears as if this would spread radially around the sun. At the edges of the clouds, it often is used to this iridescence.

Another effect occurs when light passes through small gaps in the clouds. The sun's rays here are spreading seemingly cone shape up or down now, as the pictures below illustrate.