GEOL 110 Lecture Notes - Lecture 11: Cold Front, Appalachian Mountains, Softwood
Document Summary
Convergence occurs when air flows in increasing pressure. Divergence occurs when air flows out decreasing pressure: at surface, air moves from surface high pressures (h) to low pressures (l) Air at low rises into atmosphere and then diverges in the upper atmosphere. A surface low is often associated with a high aloft and vice versa. Tendency of air is to remain in place. Air parcels resist movement or return to original spot after they move: in unstable air, parcels are rising until they reach air of similar temperature and density. Air is unstable when lighter, warm/ moist air is overlain by denser cold or dry air. Some air sinks and some air rises. Fronts: boundary between cooler and warmer air masses. Warmer air will always be lifted by the colder, denser air mass. Air masses also have different humidity levels, densities, wind patterns, and stability: different fronts. Cold front when cold air is moving into warm air.
