High-pressure area radiation and temperatures rise. At night, the absence of clouds means that outgoing longwave radiation (i.e. heat energy from the surface) is not absorbed, giving cooler diurnal low temperatures in all seasons. When surface winds become light, the subsidence produced directly under a high-pressure system can lead to a buildup of particulates in urban areas under the ridge, leading to widespread haze. If the low level relative humidity rises towards 100 percent overnight, fog can form. Strong, vertically shallow high-pressure systems moving from higher latitudes to lower latitudes in the northern hemisphere are associated with continental arctic air masses. Once
Filtered Air Positive Pressure things, these facilities can have other special hygiene control elements: Filtered Air Positive Pressure A filtered air positive pressure environment in laboratory animal science is a space that is under positive pressure with respect to the outside world. In this way, no germs that could affect the lab animals or that are a threat to the SPF status can enter the facility. To bring in new air, high efficiency particulate air filters (HEPA) are used. In some facilities, the opposite is done: negative pressure inside prevents escape of germs to the outside world. This is done when the facility does