Many courses of thermal inversions are now well understood, and their occurrence can usually be predicted by meteorologists One such cause is a high pressure subsidence When a high pressure region of the atmosphere subsides, or moves downward toward the earth where the pressure is greater, the air mass will be compressed and its temperature will rise This relatively dense warm air then will continue to move toward the earth until it meets the higher lemperature density air near the surface It was this kind of inversion that caused the A high pressure mass of air problems in London in 1952 subsides toward the earth and it compressed and heated in the process, causing a thermal inversion layer some distance above the groundMany courses of thermal inversions are now well understood, and their occurrence can usually be predicted by meteorologists. One such cause is a high pressure subsidence. When a high pressure region of the atmosphere subsides, or moves downward toward the earth where the pressure is greater, the air mass will be compressed and its temperature will rise. This relatively dense warm air then will continue to move toward the earth until it meets the higher density air near the surface. It was this kind of inversion that caused the problems in London in 1952. A high pressure mass of air subsides toward the earth and it compressed and heated in the process, causing a thermal inversion layer some distance above the ground