Pilvienväri

Pilvienväri refers to the visual appearance of clouds, specifically their color and how it is perceived. Clouds are made of water droplets or ice crystals suspended in the Earth's atmosphere. Their color is determined by how light interacts with these particles.

When clouds are thin and contain small water droplets, they often appear white. This is because the water droplets scatter all wavelengths of visible sunlight equally, a phenomenon known as Mie scattering. This scattering causes the light to be reflected in all directions, making the cloud appear bright and white.

As clouds become thicker or contain larger water droplets and ice crystals, they can appear gray or even black. This is due to the increased density of the cloud. Thicker clouds absorb and scatter more sunlight, allowing less light to pass through to the observer. The underside of very dense clouds can appear dark because the light is scattered upwards and away from the ground.

The color of clouds can also be influenced by atmospheric conditions and the time of day. During sunrise and sunset, clouds can take on hues of red, orange, and pink. This occurs because sunlight travels through more of the Earth's atmosphere at these times, scattering away shorter, bluer wavelengths of light and allowing longer, redder wavelengths to reach the clouds. Atmospheric particles like dust and pollution can also affect cloud color, sometimes contributing to more muted or even colored appearances. The perception of pilvienväri is thus a complex interplay of physical cloud properties and optical phenomena.