Evaporative coolers are an alternative to refrigerant style air conditioning and as the name suggests they use evaporation to cool a room. Put simply evaporative air cooling works by blowing warm air through moisture so that heat is lost from the air through evaporation. If you have ever had the pleasure of standing near a waterfall on a hot day then you will know that the air near the waterfall is cooler. This is in principle the same as an evaporative cooler. An evaporative cooler usually works by pumping water through pads designed to absorb moisture within the unit. A Fan then draws warm air from the room through the units and pads. This warm air leads to evaporation of the water in the pads which in turn increases the humidity of the room and cools the air. Because of this process evaporative coolers will have a stronger air cooling effect in a hot and dry environment. In a highly humid environment evaporative air cooling will have less of an effect because there is already moisture in the air.