How does snow typically form?

Snow typically forms through the process of growth on ice crystals via mechanisms like deposition, riming, or aggregation. In the atmosphere, when temperatures are below freezing, water vapor can directly transform into ice without becoming liquid first, through the process of deposition. This adds layers to existing ice crystals, leading to snowflake formation.

Riming occurs when supercooled water droplets collide with ice crystals and freeze on contact, further growing the crystal. Aggregation is the merging of multiple ice crystals to form larger snowflakes. These processes collectively describe how snowflakes develop in cold clouds.

The other options do not accurately describe the snow formation process: evaporation in air typically leads to water vapor, not solid precipitation; rain that freezes creates ice pellets rather than snow; and condensation occurs when air cools, leading to droplets of liquid water rather than ice crystals unless temperatures are below freezing.