Peggy LeMone, a senior scientist at the National Center for Atmospheric Research, did the math for Metal Floss in 2013. According to LeMone, an average cumulus cloud — the fluffy ones you typically see on a sunny day — has a water density of half a gram per cubic meter and a volume of one billion cubic meters. When you calculate the cloud's total water content, you end up with 500,000,000 grams of water, or about 1.1 million pounds.