Pressure system low pressure, while As depict anticyclonic flow or likely positions of high-pressure areas. An area of confluent streamlines shows the location of shearlines within the tropics and subtropics. Pressure system A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence that occur in upper levels of the troposphere. The formation process of a low-pressure area is known as cyclogenesis. Within the field of atmospheric dynamics, areas of wind divergence aloft occur in two areas: Diverging winds aloft ahead of these troughs
High-pressure steam locomotive High-pressure steam locomotive A high-pressure steam locomotive is a steam locomotive with a boiler that operates at pressures well above what would be considered normal. In the later years of steam, boiler pressures were typically . High-pressure locomotives can be considered to start at , when special construction techniques become necessary, but some had boilers that operated at over . Maximising the efficiency of a heat engine depends fundamentally upon getting the temperature at which heat is accepted (i.e. raising steam in the boiler) as far as possible from the temperature at which it is rejected (i.e. the steam when