It once rained inside Facebook, brought down Web cloud -- no, really Facebook and other major tech companies have data centers to support what they like to call "cloud" computing, or the ability for users to store and work with files remotely. But in the early days of Facebook's first data center, an actual indoor rain cloud brought down the company's Web cloud, Jay Parikh, Facebook vice president of infrastructure engineering, recently said. In summer 2011, Facebook's Prineville, Ore., data center suffered a problem in the building management system that caused the air used to cool the servers to reach temperatures of more than 80 degrees and the humidity to exceed 95%. As a result, the air condensed and formed a rain cloud inside the data center. QUIZ: How much do you know about Facebook? "I got a call, 'Jay, there's a cloud in the data center,' " Parikh told the Register. 'What do you mean, outside?' No, inside. It was raining in the data center. The problem occurred because Facebook was using outside air to cool its center, rather than traditional cooling systems that use a great deal of electricity, the Register report said. After the building management system broke down, it began recirculating high-temperature and low-humidity air through a water-based evaporative cooling system. That eventually caused the air to essentially become liquid and cover the servers in water. Parikh told the Register that some servers broke entirely and that for a few minutes it was possible to stand in the data center and hear the company's servers pop and fizzle. "This is one of those things," Parikh told the Register. When you are 100% air-cooled, it's awesome from an efficiency perspective, but the range you have to operate in is much, much wider. The incident hasn't occurred again, though. Parikh said that Facebook now seals its servers' power supplies with a rubber raincoat to keep water from destroying them.