Which phenomenon is primarily responsible for the formation of snowflakes?

The formation of snowflakes is primarily attributed to the Bergeron process. This phenomenon occurs in cold clouds where both supercooled liquid water droplets and ice crystals are present. Under these conditions, the ice crystals grow larger as they attract water vapor from the surrounding air, which condenses and freezes onto them. This process leads to the intricate and diverse shapes of snowflakes.

In contrast, condensation typically refers to the process where water vapor turns into liquid water, which is important in cloud formation but does not directly produce solid precipitation like snow. Evaporation is the opposite process where liquid water turns into vapor, which does not lead to snowflake formation. Collision-coalescence is more relevant to the formation of raindrops in warmer clouds, where larger droplets form by the merging of smaller ones, again not applicable to the formation of snowflakes.