Humidity is a measure of how much water vapor is present in air. The volume of water vapor that can be held in air can vary significantly with temperature and pressure; with warm air being able to hold more water vapor than cold air. Due to this, humidity is frequently expressed in terms to relative humidity (RH), which equates the actual amount of water vapor in the air compared to what the air is capable of holding under the environmental conditions (temperature and pressure) present at that time.

In many industrial processes, commercial processes, and agricultural settings it is necessary or advantageous to increase the humidity (or water content) of the air in a duct, chamber, or room. The fine atomization of water produced by misting or fog pattern spray nozzles is effective at increasing the humidity level. The small water droplets produced by these nozzles are capable of evaporating quickly, even at normal ambient temperatures, thus increasing the amount of water that is present in the air. Under most general atmospheric environmental conditions, only a relatively small amount of water is required to evaporate and effectively increase the relative humidity. BETE offers a wide variety of nozzles which can provide the low flow rates and fine atomization required for humidification applications.