Final answer:
Air masses form under conditions of light wind and high pressure, because high-pressure systems lead to air stability which is necessary for the development of air masses. Storm reports indicate that a significant drop in atmospheric pressure can lead to severe weather events like hurricanes.
Step-by-step explanation:
Air masses form in conditions that feature d. light wind and high pressure. High-pressure systems are areas where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. When the pressure is high, the air from above sinks towards the surface, becoming warmer and drier. This process does not favor the ascent of air or the formation of cloud structures, which is conducive to the formation of air masses. Conversely, low-pressure systems involve rising air that cool and condense to form clouds and precipitation, leading to different weather events.
Storm reports reveal that a significant drop in atmospheric pressure can lead to severe weather phenomena like hurricanes, characterized by torrential rainfall and strong winds. Atmospheric pressure plays a critical role in the formation and movement of storm systems, as gas moves from an area of high pressure to an area of low pressure. Thus, air masses tend to form under light wind conditions which allow for the accumulation and settling of air, and where pressure levels are typically high, creating stable conditions that are necessary for air mass development.