Turn Oven on and set to 400 degrees. Place 2 glasses with water inside oven. Leave one glass of water alone and add 2 alka-seltzers to the other. Close oven.
According to the Global Warming defenders, after a couple of hours you should have a snowstorm inside your oven.
I must be doing something wrong. The only thing I keep getting is a damn mess inside the oven. But I will follow the precepts of the Grand Pope Of Global Doom, His Excellency Al Gore and keep repeating the experiment till I get a slurpee.