Snowball is porous, so it suck melted water well. Soot is appeared when flame meets with cold show, flame just don't have time to burn completely, before it become too cold for burning.

You could repeat it with knowingly clean show from fridge. Flame should touch the snow to leave soot.

Bloody hell, think yourself, be curious, check everything, study how things work.

PS: Pouring snowball with liquid LPG at -30C (-22F) and firing it is much more entertaining.

Snowball is porous, so it suck melted water well. Soot is appeared when flame meets with cold show, flame just don't have time to burn completely, before it become too cold for burning.

You could repeat it with knowingly clean show from fridge. Flame should touch the snow to leave soot.

PS: Pouring snowball with liquid LPG at -30C (-22F) and firing it is much more entertaining.