Final answer:
The sky's blue color, sunsets appearing reddish-orange, and the blueness of distant mountains are all results of light scattering, where short wavelengths are scattered more than long wavelengths. The color of the sea is influenced by the reflection of the blue sky and other factors.
Step-by-step explanation:
The sky appears blue due to the scattering of sunlight by the Earth's atmosphere, which more strongly affects shorter wavelengths of light, such as blue, than longer wavelengths. Sunsets appearing reddish-orange: This is a result of the same scattering process. When the Sun is low on the horizon, its light travels through a thicker layer of the atmosphere, which scatters the shorter blue wavelengths and allows the longer red wavelengths to reach our eyes. The sky appears blue even on cloudy days: Cloud cover generally scatters all wavelengths more uniformly, and while this might still lead to a paler blue sky, it's not as direct a result as others listed. The blueness of distant mountains: Yes, this is due to the scattering of blue light. Particles in the atmosphere scatter blue light, which then appears to blanket distant objects, giving them a blue tint. The color of the sea on a sunny day: This is primarily due to the reflection of the blue sky on the water's surface and the absorption of other colors of light by water, rather than the direct scattering of light in the atmosphere.