Why sky appears red just before sunset?

Answer 1

The sky becomes redish/purple in the evening because of the angle in which the sun light waves penetrate the atmosphere. During the day when the sun is hiting the earth in a perpendicular way, the blue waves from the spectrum penetrate the atmosphere with more frequency than any other waves, and that's why the sky is blue in those hours. During Dawn or Dusk, when the sun is in a different angle to the earth, the Red / purple waves from the spectrum are absorved more than any others.

Answer 2

The sky appears red during sunset (and during sunrise) because there is more atmosphere between you, the observer, and the sun, and the sun's red portion of the spectrum is bent less by the atmosphere.

Answer 3

When sunlight comes from the horizon rather than from the upper part of the sky, it is passing through a larger amount of atmosphere, and as a result, it experienced a greater amount of Rayleigh scattering.

Answer 4

The sky is redder when the sun is closer to the horizon; this is because at an angle the atmosphere tends to deflect blue light and allow red light to pass through. This is because blue light has a shorter wavelength and therefore has more chances to hit atmospheric particles (such as gas molecules, water droplets, and particulates). The entire sky functions rather like an array of countless prisms; the angle of light affects the amount of atmosphere through which the light passes and thus the probability of certain colors being deflected or transmitted. This phenomenon is similar to the effect of mist to produce a rainbow, except on a larger scale; it also explains why the sky is blue most of the day. However, if your sky is getting red in the afternoon rather than the early morning or late evening, either we are using different conventions to recognize general concepts of time, or you live in an area that experiences unusual meteorological conditions to your west, which could affect the explanation; one suggestion that comes to mind is volcanic activity.

Another viewpoint: It is because the sunlight has to pass through more of the atmosphere.

However, the scientific phenomenon involved is called "scattering". Red light is

scattered less than blue light.
Red sky in morn, sailors take warn. Red sky at night, sailors delight. This means that because the earth rotates towards the east, In the morning, if you see red, it means you are heading into a weather system due to the increased moisture in the atmosphere. (sailors take warn.) If you see this same red in the afternoon, the moisture is to the west of you and not a direct threat. (sailors delight). The origin of the saying is unknown, although a form of it appears in The Bible (Matthew 16:2-3). It has some basis in science and is a fairly good predictor of-though no guarantee-of weather at the mid latitudes in the Northern Hemisphere, where storm systems generally follow the jet stream from west to east. A red sky in the morning indicates a sun rising in clear eastern skies casting its rays on storm clouds approaching from the west. At night the clear sight of the red setting sun would tell a sailor that no storms are to the west. See the related link for more information.
The air is dry when there is a red sky in the afternoon or evening. "Red sky at night sailor's delight. Red sky in the morning sailors' warning."
The sun hits the clouds at an angle so it makes the sky look red

Answer 5

During sunset, the sun is low on the horizon, causing its light to pass through more of the Earth's atmosphere. This scattering of light by the atmosphere causes shorter wavelength colors like blue and green to scatter out, leaving longer wavelength colors like red and orange to dominate the sky's appearance. This phenomenon is known as Rayleigh scattering.

Answer 6

Refraction of the sun's light below the hoizon. The red light is the one at the lower end of the refraction and is seen last. The red light refracts and lights up the clouds.

Answer 7

It is gods work repeant now