Question

Why does the sky appear white sometimes?

Answer 1

Hint: When a ray of light passes through various layers of the atmosphere, the ray of light undergoes several phenomena like refraction, reflection and scattering as it interacts with various atmospheric particles of various sizes. The white appearance of the sky sometimes is due to the scattering of incoming solar radiation by large sized particles.

Complete step by step answer:
Earth’s atmosphere is composed of many substances like dust particles, gas molecules, water droplets, ice crystals and other hydrometeors. When solar radiation comes from Sun to Earth’s surface it passes through various layers of the atmosphere and interacts with different particles of different sizes present in the atmosphere. Some of the particles have size smaller than the wavelength of the light whereas some particles have size larger than the wavelength of the light. The particles which have larger size compared to the wavelength of the light scatter the incoming solar radiation and their scattering intensity is of the same extent for all the wavelengths of the white light. As the scattering intensity is nearly the same for all wavelengths, to human eyes it appears white. Thus, the sky sometimes appears white.

Note:
Sky mostly appears white during the hot days. This is because the size of water droplets increases during the hot days due to the rise in temperature . As stated earlier, particles of larger size compared to wavelength of light the scattering intensity is nearly the same for all wavelengths and hence the sky appears white mostly during the hot days.