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A sunbeam, in meteorological optics, is a beam of sunlight that appears to radiate from the position of the Sun. Shining through openings in clouds or between other objects such as mountains and buildings, these beams of particle-scattered sunlight are essentially parallel shafts separated by darker shadowed volumes.
Crepuscular rays are noticeable when the contrast between light and dark is most obvious. Crepuscular comes from the Latin word crepusculum, meaning "twilight". [2] Crepuscular rays usually appear orange because the path through the atmosphere at dawn and dusk passes through up to 40 times as much air as rays from a high Sun at noon.
Therefore, the sunbeam hitting the ground at a 30° angle spreads the same amount of light over twice as much area (if we imagine the Sun shining from the south at noon, the north–south width doubles; the east–west width does not). Consequently, the amount of light falling on each square mile is only half as much.
Extreme UV and X-rays are produced (left of wavelength range) but comprise very small amounts of the Sun's total output power (area under the curve). Although the solar corona is a source of extreme ultraviolet and X-ray radiation, these rays make up only a very small amount of the power output of the Sun (see spectrum at right).
Anticrepuscular rays, or antisolar rays, [1] are meteorological optical phenomena similar to crepuscular rays, but appear opposite the Sun in the sky. Anticrepuscular rays are essentially parallel , but appear to converge toward the antisolar point , the vanishing point , due to a visual illusion from linear perspective .
Its appearance as a vertical line is an optical illusion, resulting from the collective reflection off the ice crystals; but only those that are in the common vertical plane, direct the light rays towards the observer (See drawing). This is similar to viewing a light source on a body of water.
Examples of volumetric lighting are seeing sunbeams shining through a window and seeing sunbeams radiating when the Sun is below the horizon, also known as crepuscular rays. The term seems to have been introduced from cinematography and is now widely applied to 3D modeling and rendering , especially in the development of 3D video games .
Sunlight forms a light beam (a sunbeam) when filtered through media such as clouds, foliage, or windows. To artificially produce a light beam, a lamp and a parabolic reflector is used in many lighting devices such as spotlights, car headlights, PAR Cans, and LED housings. Light from certain types of laser has the smallest possible beam divergence.