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Calculate the sunset time, which is the solar noon time plus the sunset hour angle in degree divided by 15; Use the sunset time as input to the solar geometry routine to get the solar azimuth angle at sunset. An interesting feature in the figure on the right is apparent hemispheric symmetry in regions where daily sunrise and sunset actually occur.
Because the shorter wavelength components, such as blue and green, scatter more strongly, these colors are preferentially removed from the beam. [2] At sunrise and sunset, when the path through the atmosphere is longer, the blue and green components are removed almost completely, leaving the longer wavelength orange and red hues we see at those ...
[9] [10] [12] [15] Ash from volcanic eruptions, trapped within the troposphere, tends to mute sunset and sunrise colors, while volcanic ejecta that is instead lofted into the stratosphere (as thin clouds of tiny sulfuric acid droplets), can yield beautiful post-sunset colors called afterglows and pre-sunrise glows.
The color temperature of daylight varies with the time of day. It tends to be around 2,000 K shortly after sunrise or before sunset, around 3,500 K during "golden hour", and around 5,500 K at midday. The color temperature can also change significantly with altitude, latitude, season, and weather conditions.
Twilight occurs according to the solar elevation angle θ s, which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest the horizon), nautical twilight, and astronomical twilight (farthest from the horizon).
Blue hour usually lasts about 20–96 minutes right after sunset and right before sunrise. Time of year, location, and air quality all have an influence on the exact time of blue hour. [7] For instance in Egypt (every 21st of June), when sunset is at 7:59 PM: blue hour occurs from 7:59 PM to 9:35 PM.
The yellow color is due to the presence of pollutants in the smoke. Yellowish clouds caused by the presence of nitrogen dioxide are sometimes seen in urban areas with high air pollution levels. [22] Red, orange and pink clouds occur almost entirely at sunrise and sunset and are the result of the scattering of sunlight by the atmosphere.
When the sky is clear, it is blue colored, and if there are clouds or haze, bronze, orange and yellow colors are seen. Some bright stars and planets such as Venus and Jupiter are still visible to the naked eye at civil dawn. This moment marks the start of civil twilight, which lasts until sunrise. [6]