Why does sun appear red at sunrise and sunset?
Why does the Sun appear red at sunrise?
At the time of sunset or sunrise, the Sun and its surroundings appear red because of the scattering of light. At the time of sunset or sunrise, the light rays from the Sun have to travel a long distance to reach our eyes through the Earth's atmosphere. In other words, we can say that when we look towards the horizon, we are looking through more of Earth’s atmosphere than when we look overhead. The light reaching our eyes is rich in red color as blue light is largely scattered away by the particles present in the Earth's atmosphere.
The Sun appears red at sunrise because of the scattering of light by the atmospheric particles. During sunrise, the light from the Sun has to travel a longer distance through the atmosphere to reach the observer. During this, most of the shorter wavelengths present in it are scattered away from our line of sight by the molecules of air and other fine particles in the atmosphere. So, the light reaching us directly from the rising Sun consists mainly of longer wavelength red color due to which the Sun appears red.
At sunrise, the sun is near the horizon; hence, sunlight has to travel a longer distance through the atmosphere to reach us. During this journey, most of the blue colour present in sunlight, which is of shorter wavelength, gets scattered from our line of sight. Thus, the red colour present in sunlight, which has a longer wavelength and is scattered the least, reaches our eye. As we see red light everywhere above, the sun and the surrounding sky appear red at sunrise.