Eli5: If water is transparent, why are clouds white?

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Eli5: If water is transparent, why are clouds white?

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Anonymous 0 Comments

Gretchen you can’t ask clouds why they’re white!

Also, clouds are white because light from the Sun is white. As light passes through a cloud, it interacts with the water droplets, which are much bigger than the atmospheric particles that exist in the sky.

Anonymous 0 Comments

In a word- diffraction.

Basically, when lots of surfaces and angles are introduced to ray-paths of light (which implies there are different materials for the light to traverse – with the important distinction being changes in those materials’ densities), the light ‘bounces’ around instead of traveling in a straight line. Enough chaotic, criss-crossing light rays creates opaqueness – in the case of liquid water, light sees it as a single continuous material of constant density and the ray-paths pass linearly through (so that looks clear to us). In the case of clouds, which are millions droplets, the light see it as millions of discrete objects (which it physically is) and refracts each time passing through the curves droplet surfaces, redirecting the ray-path in an amount proportional to the angle relative to the surface interface & difference in material densities (this is known as Snell’s Law) – and we can’t see through the chaos.

Anonymous 0 Comments

You can’t just ask clouds why they’re white?

Anonymous 0 Comments

Everything you see is just light bouncing and having different wavelengths. Your brain perceives them as colors. So basically the light hits. Same as water looks blue even though it’s transparent.

Anonymous 0 Comments

Clouds are made of droplets. Water droplets scatter light. When you have that many droplets hanging out near each other the light gets scattered so much that we perceive it as white light

Anonymous 0 Comments

Water freezes when it’s that high in the atmosphere. After water has been evaporated into the atmosphere it creates little crystalline structures that form clouds. They appear white because they refract light and all colors together are white. Think about a prism. You can see all the colors that combine to make white light through a prism. That’s why the clouds appear white.

Anonymous 0 Comments

Nothing is truly “transparent”, but more properly translucent.

In other words: some but not all light passes through water.

Besides clouds, you can see large bodies of water block light. You don’t have to go very far underwater before it gets really dark!

In the case of clouds, they’re white not because they’re blocking light, but because they’re diffusing and dispersing it. Think frosted glass.

Each time you get an interface between materials like water and air or glass and air, you’ve got a place where light will bend. The drops of water in a cloud are each bending the light and scattering it, which adds up to something bright (they’re kinda white) but that also obscures your view.

Anonymous 0 Comments

If glass is transparent, why is a handful of tiny glass chips white? For the same reason. All those small particles (droplets of water in the clouds, or the glass chips) reflect light in all directions, until light has a hard time getting through, and is dispersed in all directions.

The result is a white opaque mass.

Anonymous 0 Comments

Have a look at the side of a glass full of water. It’s transparent, yes, but distorted. Like a magnifying glass, the curved surface where it switches from air to glass and water makes the light bend, which makes things look all, well, bent. But the glass is big enough that you can still make things out through it.

Now imagine a hundred glasses of water in a big cluster on a table, and imagine looking through them all. The image would be so scrambled, it would be like trying to watch free porn on cable. (Hey, five-year-olds: don’t try to watch porn. Also, stop living 20 years in the past, it’s weird.)

A cloud is made of up a *huge* number of *very* small droplets of water. They’re curved, like the glasses, so each one distorts light. And because there are so many, they’re absolutely impossibly scrambled. We say they “scatter” light, which means they mix it up so much we could never see what the original image was, like squirting colors of paint into a cup and stirring them together. And like the paint, what we get depends on what colors of light went in.

Now, in the sky, you might think that would make a cloud blue, because you’d only be stirring up the blue light from the sky behind it. But it’s not just the blue sky that adds light to a cloud, because the sun shines directly on a cloud too! So it’s all of the colors that sunlight makes, which, mixed together, give you white.

At sunset, though, the sunlight has more air to go through before it gets to the clouds that you can see. The sun is farther away from *your* clouds now and closer to other people’s clouds—people in a different timezone, where it’s not sunset yet. Redder light has an easier time getting through all that air (for reasons best left to another answer), which means the light that reaches your clouds is redder. When the clouds mix up *those* colors, you get a beautiful sunset!

Anonymous 0 Comments

Water isn’t transparent. Ever looked down into a deep river?