Explain why, when the sun is overhead at noon, it appears white, but when the same sun is near the horizon at sunset, it appears red.
Explain why, when the sun is overhead at noon, it appears white, but when the same sun is near the horizon at sunset, it appears red.
When the sun is at the horizon, the rays of light have to pass through many layers of the atmosphere before they reach our eyes. Due to the varying optical densities of the atmosphere, this light is heavily refracted.
The shorter wavelengths, such as blue and violet, are immediately scattered away by the atmosphere, and hence the light that reaches our eyes is mainly of longer wavelengths that are less scattered, making the sun look reddish-orange in colour.
However, when the sun is directly overhead, it does not pass through many layers of the atmosphere. Thus, the shorter wavelengths are not scattered. The light that reaches our eyes has all the wavelengths, and we hence see the sun as white in colour.
When the sun is at the horizon, the rays of light have to pass through many layers of the atmosphere before they reach our eyes. Due to the varying optical densities of the atmosphere, this light is heavily refracted.
The shorter wavelengths, such as blue and violet, are immediately scattered away by the atmosphere, and hence the light that reaches our eyes is mainly of longer wavelengths that are less scattered, making the sun look reddish-orange in colour.
However, when the sun is directly overhead, it does not pass through many layers of the atmosphere. Thus, the shorter wavelengths are not scattered. The light that reaches our eyes has all the wavelengths, and we hence see the sun as white in colour.
