If the sky is blue, why are clouds white?
Unlike Rayleigh scattering, where the light waves are much smaller than the gases in the atmosphere, the individual water droplets that make up a cloud are of similar size to the wavelength of sunlight.
When the droplets and light waves are of similar size, then a different scattering, called ‘Mie’scattering, occurs.
Mie scattering does not differentiate individual wave length colors and therefore scatters all wave length colors the same. The result is equally scattered ‘white’ lightfrom the sun and therefore we see white clouds.
Yet, clouds do not always appear white because haze and dust in the atmosphere can cause them to appear yellow, orange or red.
And as clouds thicken, sunlight passing through the cloud will diminish or be blocked, giving the cloud a grey color.
If there is no direct sunlight striking the cloud, it may reflect the color of the sky and appear bluish
Why clouds appear and disappear?
The atmosphere is in constant motion.
As air rises drier air is added (entrained) into the rising parcel so both condensation and evaporation are continually occurring. So cloud droplets are constantly forming and dissipating.
Clouds form and grow when there is more condensation on nuclei than evaporation from nuclei. Conversely, they dissipate if there is more evaporation than condensation.
Thus clouds appear and disappear as well as constantly change shape.
How do clouds stay in the sky and don’t fall to the ground?
Each cloud is made of millions of tiny water droplets.
Each droplet is so small and light that it can float in the air.
If some of those droplets grow larger, they’ll get heavier and fall to the ground as raindrops.
The cloud droplets or crystals are so small that their terminal velocity, the highest velocity possible as an object falls through a fluid, is negligible.
They are falling but they fall so slowly that they appear to be suspended in the air.
What are clouds made of?
Clouds that are low in the atmosphere are made of liquid water droplets.
Clouds that are high in the atmosphere are made of ice crystals because it’s cold up there.
For more information https://htschool.hindustantimes.com/editorsdesk/knowledge-vine/5-fascinating-facts-about-clouds
