what happens when an air mass is pushed up and over a mountain range
Orographic lift
title: Orographic lift text: Orographic lift Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation. Precipitation induced by orographic lift occurs in many places throughout the world. Examples include: The highest precipitation amounts are found slightly upwind from the prevailing winds at the crests of mountain ranges, where they relieve and therefore the upward lifting is greatest. As the air descends the title: Mountain text: exponentially with height. However, when air is hot, it tends to expand, which lowers its density. Thus, hot air tends to rise and transfer heat upward. This is the process of convection. Convection comes to equilibrium when a parcel of air at a given altitude has the same density as its surroundings. Air is a poor conductor of heat, so a parcel of air will rise and fall without exchanging heat. This is known as an adiabatic process, which has a characteristic pressure-temperature dependence. As the pressure gets lower, the temperature decreases. The rate of decrease of temperature with elevation title: Orographic lift text: can create a variety of cloud effects. Orographic lift Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation. Precipitation induced by orographic lift occurs in many places throughout the world. Examples include: The highest precipitation amounts are found slightly upwind from the prevailing winds at the crests of mountain ranges, where they relieve and therefore the upward lifting title: Air mass text: east, while warm fronts move poleward. Because of the greater density of air in their wake, cold fronts and cold occlusions move faster than warm fronts and warm occlusions. Mountains and warm bodies of water can slow the movement of fronts. When a front becomes stationary, and the density contrast across the frontal boundary vanishes, the front can degenerate into a line which separates regions of differing wind velocity, known as a shearline. This is most common over the open ocean. Air masses can be modified in a variety of ways. Surface flux from underlying vegetation, such as forest, acts title: Convective instability text: Convective instability In meteorology, convective instability or stability of an air mass refers to its ability to resist vertical motion. A "stable" atmosphere makes vertical movement difficult, and small vertical disturbances dampen out and disappear. In an "unstable" atmosphere, vertical air movements (such as in orographic lifting, where an air mass is displaced upwards as it is blown by wind up the rising slope of a mountain range) tend to become larger, resulting in turbulent airflow and convective activity. Instability can lead to significant turbulence, extensive vertical clouds, and severe weather such as thunderstorms. Adiabatic cooling and heating are phenomena