Final answer:
The collision of low-density air with high-density air results in the warm air rising over the cold air, leading to cloud formation and weather events. Changes in air density with altitude affect weather and the need for supplemental oxygen at high altitudes.
Step-by-step explanation:
When an air mass with low density, which is typically a warm air mass, collides with a high-density air mass, which is usually a cold air mass, the warmer, less dense air rises over the cooler, denser air. This process is a key mechanism in the formation of weather fronts. The rising of the warm air mass can lead to the cooling and condensation of water vapor, resulting in cloud formation and potential precipitation. Moreover, the interaction between different air masses can lead to the development of various weather phenomena, from clear conditions when a cold front clears out the air to severe storms as a warm front brings moist, unstable air into an area.
The change in air density with altitude also affects weather patterns. As one climbs a mountain, the air becomes less dense, a phenomenon also illustrated by the weight of air decreasing as one ascends to high altitudes, such as on Mount Everest. This decrease in air density is why climbers often need oxygen tanks to compensate for the lower oxygen levels available.