The largest known snowflake in history measured 15 inches across! We find out about the physics and chemistry of snow and what conditions we’ll need to have a White Christmas this year. Dr. Kenneth Libbrecht is Professor of Physics at Caltech; David A. Robinson is The New Jersey State Climatologist and a Professor of Geography at Rutgers University, where he conducts research at the Global Snow Lab.

Weigh in: What’s your favorite memory or experience with snow?