How can clouds hold so much water?
Because they're very big! Cumulo-nimbus clouds (the big, puffy ones) can extend tens of thousands of feet up into the atmosphere. Even the thinner nimbo-stratus (the flat ones) can still be several thousand feet thick...both can hold 1000 cloud drops per cubic inch! And consider this...one inch of rain over just one square mile...is equivalent to 17.4 million gallons!