Is it time for a revolution in snow gauge design? A new study by NCAR scientists suggests so. During a field experiment in February, Julie Thériault and her colleagues found that the accuracy of snow gauge measurements changes with the size and shape of snow crystals, the speed at which they fall, and the wind. For example, during high winds, snow tends to blow over the gauge instead of falling inside. Installing a shield around the gauge to prevent this only confuses the matter because both the gauge and the shield present an obstacle to natural airflow patterns. Smaller and lighter snowflakes may interact with the gauge and the shield differently than larger ones.
The scientists collected snowflakes inside and outside a gauge, both with and without a shield, and photographed them every 20 minutes to analyze crystal type and size. They also used a computer model to simulate wind flow and reveal the trajectories of different crystals falling through the atmosphere.
KIMBRA CUTLIP is a freelance writer and former assistant editor for Weatherwise.