It's a cooling unit as Mamy says. Although I dislike tennis played on cement and hate the razamataz that accompanies the prize giving (after a suitable interval to allow the stagehands to build the stage) "Flushing Meadows" (a misnomer if ever there was one) gets a few things right. Providing an air cooler for the players is certainly one of those things. You will see the same thing provided for Formula One drivers when they are waiting on the grid to start the race. They have a bit more of an excuse as they are clad head to toe in three layers of fireproof overalls rather than a skirt and T-shirt.
"2. Clay tennis courts. Clay courts mainly come in two different forms: The red clay court is a coarse mixture made from brick,..."
Assuming they don't play on whole bricks, I'm assuming the red powder they quaintly call "clay" consists of crushed bricks. If not please enlighten me. But whatever it is, I still don't like watching tennis played on it.