Ah, the physics of snowflakes, explained so simply by Kenneth Libbrecht at CalTech who created where you can find answers to everything you’ve ever wanted to know about snowflakes. See stunning photos, learn how to make snowflake fossils, and make your own ice spikes. Endless resources on his site. Here are some of Ken’s answers to questions I’ve long pondered:

What is a snowflake? Snowflakes are not frozen raindrops.  Sometimes raindrops do freeze as they fall, but this is called sleet. Sleet particles don’t have any of the elaborate and symmetrical patterning found in snow crystals.  Snow crystals form when water condenses directly into ice, which happens in the clouds.The patterns emerge as the crystals grow.(See diagram, below.)

Why do they have six arms? (See crystal faceting.)

Why is snow white? (Hint: same reason a pile of crushed glass looks white.)

Is it ever too cold to snow? (No but super cold temperatures often result in fewer flakes.)

So, where’s the best place to see snowflakes? Ken can use your help determining the answer, citizen scientists! Email Ken at with your suggestions and pictures! He and his students will examine the images and feed them into a growing database they’ve created to track snowflake formations by location.

(Thanks to my Dad for sending the link to me!)