Low-pressure area Low-pressure area A low-pressure area, low, depression or cyclone is a region on the topographic map where the atmospheric pressure is lower than that of surrounding locations. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the troposphere. The formation process of a low-pressure area is known as cyclogenesis. Within the field of meteorology, atmospheric divergence aloft occurs in two areas. The first area is on the east side of upper troughs, which form half of a Rossby wave within the Westerlies (a trough with large wavelength that extends through the troposphere). A second
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