Why do people say "blue sky and white clouds" when the weather is fine? "Blue sky and white clouds", why?

White clouds are made up of many tiny water droplets.

The size of these water droplets is much larger than the wavelength of light waves, so they will form reflections on the surface of water droplets. The size of these water droplets is much larger than the wavelength of light waves, so they will form reflections on the surface of water droplets.

Because the incident light will reflect in different directions, it looks white. Because the incident light will reflect in different directions, it looks white.

(All colors of visible light will be reflected-it will form a white feeling and see a colorful world) (All colors of visible light will be reflected-it will form a white feeling and see a colorful world)

The wavelength of visible light is about 0.3-0.7 micron (one micron = 10 -6 m = 10 -3 cm). The wavelength of visible light is about 0.3-0.7 micron (one micron = 10 -6 m = 10 -3 cm).

Want to know the wavelength? Want to know the wavelength? Think about it, how many microns is the width of hair? Think about it, how many microns is the width of hair?

Further hint: how about estimating the width of several hairs and putting them together about one centimeter? Further hint: how about estimating the width of several hairs and putting them together about one centimeter? )

When water drops are too large, they will absorb light (absorbed after penetration), so they will form a dark color! When water drops are too large, they will absorb light (absorbed after penetration), so they will form a dark color!

The so-called "dark clouds cover the sun"! The so-called "dark clouds cover the sun"!