A device for evaporative cooling of large masses of air suitable for cooling structures utilized to shelter commercial animals, such as cows and the like, includes a member having a gas inlet, a gas outlet and a hollow interior extending between the inlet and outlet. A fan and motor are associated with the inlet for moving air into the inlet creating an air stream within the interior of the member. A plurality of vanes are located within the interior of the member for introducing a torsional component into the air stream passing through the member such that the air stream moves through the member in a spiral pathway. As the air stream spirals through the member, a spray of water is introduced into the member. The spray becomes incorporated into the spirally moving air stream to reduce the temperature of the air stream. After exiting out of the outlet of the member, the air stream is directed toward the animals of commercial interest to cool both the animals and their immediate surroundings. The device is extremely effective in modifying the environment of dairy cows and the like in climates having elevated temperatures.