Define cooling tower "range" as it applies to cooling towers.

The answer to the range of a cooling tower is the difference between the temperature of the water going in and the temperature of the water going out of the tower.

Explanation:

Cooling towers are used to cool a stream of water using the air of the environment where it's placed or installed. In theory, the lowest temperature the water can be cooled to would be the wet bulb temperature (temperature of the air going in the cooling tower). The range would be the difference (R=Ti-To) between the temperature of the hot water going in and the cooler water going out.