Final answer:
As air is pushed upward over an obstacle, it expands and cools due to lower pressure, which can lead to condensation and cloud formation, contributing to various weather events.
Step-by-step explanation:
When an air mass is pushed upward over an obstacle, it undergoes adiabatic cooling, convection, and possibly condensation. As air rises, the pressure decreases, which allows the air to expand.
This expansion cools the air, and if the air contains enough moisture, the water vapor may condense into clouds. This process is similar to what happens with hot air balloons, where hot air rises due to expansion, creating a buoyant force. The rising air can lead to weather phenomena, such as thunderheads and hurricanes, due to the positive feedback mechanism where condensed water releases heat, causing the air to rise further and potentially forming violent storms.