Evaporative air coolers are also known as swamp coolers, desert coolers and wet air coolers. These all create cooling through evaporative technology: a powerful fan blows air through a watery pad; the air causes the water to evaporate and the resulting airflow is significantly cooler and moister. The sensation is similar to a refreshing, lakeside breeze. In the right conditions, evaporative cooling can decrease its surrounding temperatures by up to 15°F. Evaporative air coolers work best in hot regions with low humidity.