Crepuscular rays are

sunbeam 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 sunl ...

s that originate when the Sun is just below the

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ...

, during the twilight period.

Crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylig ...

rays are noticeable when the contrast between light and dark is most obvious. Crepuscular comes from the Latin word , meaning "twilight". Crepuscular rays usually appear orange because the path through the atmosphere at sunrise and

sunset Sunset, also known as sundown, is the daily disappearance of the Sun below the horizon due to Earth's rotation. As viewed from everywhere on Earth (except the North and South poles), the equinox Sun sets due west at the moment of both the spring ...

passes through up to 40 times as much air as rays from a high Sun at midday. Particles in the air scatter short- wavelength light (blue and green) through Rayleigh scattering much more strongly than longer-wavelength yellow and red light. Loosely, the term ''crepuscular rays'' is sometimes extended to the general phenomenon of rays of

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...

that appear to converge at a point in the sky, irrespective of time of day. A rare related phenomena are anticrepuscular rays which can appear at the same time (and coloration) as crepuscular rays but in the opposite direction of the setting sun (east rather than west).

References

External links

{{optics-stub Atmospheric optical phenomena Sun

See also

References

External links