Why are snow flakes white?

A snowflake consists of approximately 100,000,000,000,000,000,000 molecules of water. On average. This is where the ‘no two snowflakes are alike’ thing comes from. A particular arrangement of that many tiny bits of molecule is unlikely to replicate that often, as you can imagine.

Ice isn’t perfectly clear, it’s translucent. So through any chunk of ice, when light hits it, a certain amount is bounced in a random direction (essentially, it’s not really ‘random’ but it may as well be with snow, as the arrangement of the ice molecules is random, or effectively so). Basically, as the light hits each little fragment within the snowflake, or the pile of snow, some light is sent back, and some is sent on, often to bounce into other bits of snow, which do the same.

The effect of this is for snow to reflect a roughly equal amount of all the frequencies of visible light. When you get all the frequencies teamed up, you get white light.

That’s the science bit. It’s a little rough around  the edges, but it makes sense, right? Basically, you’ve got this big translucent random structure, and it’s unpredictability ensures that the law of averages pushes out the white light, and that’s what we see.

It’s fascinating how that random build up of ice molecules leads to all of the cool and fun things about snow.

It’s hard to create ice molecules in a cloud, but easier if there’s already one there. So you get the odd one or two in a given space, and it swirls around the cloud picking up droplets and adding them to the frozen structure of itself. The whole thing builds up until it’s heavy enough to fall out of the cloud (on the way out it probably picks up a few more bits and bobs).

And then it falls patiently and erratically to earth.

And that random structure makes it fluffy and light. Full of air until trodden or packed tight with gloves. Built into temporary structures. Snowmen, snowballs and snow angels.

And it shimmers and glistens in the sunlight.

My favourite thing is to eat snow. Just take a scoop and drop it in your mouth. It melts (obviously) but not quite fast enough. So you get to chew this dreamy cloud of water as it explodes around your mouth.

And I love the crunch. The structure collapsing, but in such an organised fashion. Such a firm crispy sound.

And it’s sad that it melts, but it’s also magic how the world reappears unchanged after it leaves.

First everything changes perspective. Glittery white abandoned on every surface. People are all smiling or wobbling. You look at buildings you see every day and smile at the newness, the cleanness, the textures changed.

Then it runs away. Overnight there is nothing left. The morning exposes the world again. As it was.

But it’s still cleaner somehow. More surprising.

Snow isn’t magic. It makes perfect scientific sense.

But it looks it. And that’s enough.

Illustration by Henry.

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About Alabaster Crippens

Learner. Guesser. Thinker and Stinker.
This entry was posted in Questions by Clair, Special Guest Illustrations. Bookmark the permalink.

2 Responses to Why are snow flakes white?

  1. Pingback: Let It Snow | 62Stockon *

  2. Pingback: What is the best question ever? | Unstruck

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