For many students across the U.S., winter brings the possibility of a snow day! Heavy snowfall can cover sidewalks and make roads dangerous, forcing schools to close. Students then get to stay home to sip hot chocolate, go sledding, and have snowball fights!
For snow to fall, local conditions must be just right. Snow forms in clouds when temperatures hit or dip below 0°C (32°F)—water’s freezing point. As droplets of water turn from liquid to solid, their molecules arrange into a repeating pattern, creating six-sided crystals. But snowflakes won’t start piling up unless temperatures near the ground are similarly cold. If it’s too warm, the precipitation will ultimately fall as sleet or freezing rain.