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What happens inside a cloud?
Micro-scale Processes - Snow Formation Snow forms in clouds that are between -35 and 0 C (-31 to 32 F). We already discussed the importance of vapor diffusion in ice formation, but two other processes enable ice crystals to grow large enough to fall as snow or hail. First, aggregation is the process of ice and snow crystals sticking to each other through collision and adhesion. This occurs at temperatures that are just below freezing (-1 to -4 C, or 25 to 30 F). As water freezes, it releases heat, so a pseudo-liquid film can form on the ice crystal surfaces. This liquid layer enables colliding crystals to freeze together. The second process is riming, which is the adhesion of a supercooled water droplet to an ice or snow crystal. Riming creates an accumulation of white or milky granular ice, rather than a pristine snowflake. Once an ice crystal or snowflake has undergone so much riming that it is no longer identifiable as a distinct crystal, it is called graupel. Riming is also very important in hail formation. Did you know that when something freezes, heat is released? You can read about that here! Next page -> Micro-scale processes - snow formation continued Links and resources
Micro-scale Processes - Snow Formation Snow forms in clouds that are between -35 and 0 C (-31 to 32 F). We already discussed the importance of vapor diffusion in ice formation, but two other processes enable ice crystals to grow large enough to fall as snow or hail. First, aggregation is the process of ice and snow crystals sticking to each other through collision and adhesion. This occurs at temperatures that are just below freezing (-1 to -4 C, or 25 to 30 F). As water freezes, it releases heat, so a pseudo-liquid film can form on the ice crystal surfaces. This liquid layer enables colliding crystals to freeze together. The second process is riming, which is the adhesion of a supercooled water droplet to an ice or snow crystal. Riming creates an accumulation of white or milky granular ice, rather than a pristine snowflake. Once an ice crystal or snowflake has undergone so much riming that it is no longer identifiable as a distinct crystal, it is called graupel. Riming is also very important in hail formation. Did you know that when something freezes, heat is released? You can read about that here! Next page -> Micro-scale processes - snow formation continued Links and resources
