Sunlight is white. So why is the sky blue?

White light is every colour at once.

In the air, molecules knock light aside.

Blue is knocked aside far more than red.

About 6 times as often.

That blue flies off in every direction.

So it reaches your eye from all over the sky.

That is the blue sky.

At sunset, the light crosses far more air.

The blue is knocked out on the way.

What reaches you is red.

Cloud droplets are far bigger than molecules.

They knock every colour aside alike: white.

The blue sky is light knocked aside. The red sunset is what is left.