While it's too soon to know what the real chances are of having a white Christmas, even if it's 70 degrees and sunny, there’s still a way to experience the seasonal beauty of snow without ever having to put on a winter coat.
In a video for Science Friday, Caltech physicist and snowflake expert Ken Libbrecht illustrated how to grow snowflake-like ice crystals inside a two-liter soda bottle. To start, you need to assemble your materials. Most of the items—including a plastic bottle, bucket, sponge, fishing line, paper clip, and pins—can be easily found around your home. The most important component, though, is dry ice—which also happens to be the hardest one to find (Libbrecht recommends checking your local grocery store).
The dry ice goes around the outside of the bottle, which is outfitted with a string hanging from a wet sponge on the inside. The warm air around the top of the bottle, where the sponge is, creates water vapor, which crystallizes around the string. Within an hour, you'll have cultivated a large, feathery crystal in the center of your makeshift snowflake machine.
Even though the final product resembles a snowflake, it's technically frost (snowflakes form in clouds from thousands of water droplets, not from vapor). Libbrecht has been growing his own snowflakes for years, though the system he uses in his lab is slightly more sophisticated. After learning how to grow a snowflake at home, be sure to check out some of Libbrecht’s own exquisite creations on his website.