Minecraft wiki entry for Parity_issue_list, associated text: Is affected by gravity.[feedback 13]
When falling on other snow, it'll add the layer count together and add an additional few.
While snowing snow randomly stacks together to have random patches, opposed to being completely flat.
Melts in snowless biomes.
Generates and can be placed on packed ice, blue ice, and dirt path (which will not change to dirt).