Humidifying systems require a moderate amount of spray to achieve the desired level of humidity. The amount of water needed to raise the humidity in a given environment depends on three factors:
1. The initial humidity level of the surrounding environment
2. The rate at which air in the space is exchanged with the wider environment, is determined by ventilation and air movements
3. The temperature of the room, affects both evaporation rates and the overall capacity of the air to carry water
To achieve fast humidification with a spray nozzle, one needs to keep the droplet size as small as possible and distribute the water over a wide area. This allows the small droplets to quickly evaporate into the air, raising the humidity level.
The rate at which water evaporates from any system depends on heat, wind, surface area, and surrounding humidity. As humidity increases, the rate of evaporation also increases, as more water is held in the air for heat to act on. Humidifying systems take advantage of this fact. By increasing the level of moisture in the air, the rate of evaporation can be increased, thereby maintaining a consistently higher level of humidity through continuous or periodic spraying. Of course, there is a limit to how much water the air can hold, and once a certain level is reached, condensation or precipitation will occur.