Air conditioning. Cool heaven for those who have it, blazing hell for those who don't. It didn't used to be terribly common in broadcast engineering, but it's become moreso in the last ten years. The reason is that, more and more, audio processors, RDS encoders, audio encoders/decoders, studio/transmitter links, remote control systems, and even the transmitters themselves, have all become increasingly "computer-like" with IC's, hard disk drives, power supplies, electrolytic capacitors and the like. All things that fail quickly when operated in temperatures above 80 or so, and the warmer it gets, the faster they fail!