low - pressure air pressure is associated with warm air rising.
low - pressure air pressure is associated with warm air rising.
which type of air pressure is associated with warm air rising?
low - pressure
a surface low can have a variety of causes for forming. topography can force a surface low to form when an existing baroclinic wave moves over a mountain barrier; this is known as "lee cyclogenesis" since the low forms on the leeward side of the mountains. mesoscale convective systems can spawn surface lows which are initially warm core. the disturbance can grow into a wave-like formation along the front and the low will be positioned at the crest. around the low, flow will become cyclonic, by definition. this rotational flow will push polar air equator-ward west of the low via its trailing cold front, and warmer air will push poleward low via the warm front. usually the cold front will move at a quicker pace than the warm front and “catch up” with it due to the slow erosion of higher density airmass located out ahead of the cyclone and the higher density airmass sweeping in behind the cyclone, usually resulting in a narrowing warm sector. at this point an occluded front forms where the warm air mass is pushed upwards into a trough of warm air aloft, which is also known as a trowal (a trough of warm air aloft). all developing low pressure areas share one important aspect, that of upward vertical motion within the troposphere. such upward motions decrease the mass of local atmospheric columns of air, which lower surface pressure.
cyclogenesis
unlike atmospheric convection—the ordinary process of lower, warm air rising—inversions leave cooler air suspended below warm air, preventing the lower air from rising and trapping airborne pollutants that would ordinarily disperse in the atmosphere. such weather events are common, but they are usually followed by a strong cold front that brings an influx of clean air and disperses pollutants before they have enough time to become highly concentrated; in this case, a cold front approaching west through southern canada was delayed. when explained in less formal terms, the process of an inversion causing a smog event has been compared to a lid that holds in pollutants or a balloon that fills with pollutants. in general, smog events occur not because of a sudden increase in a region's output of pollution, but rather because weather conditions like stagnant air prevent the dispersal of pollutants that were already present.
1966 new york city smog