What are the characteristics of an air mass labeled mP?

The characteristics of an air mass labeled mP, which stands for "maritime Polar," are indeed cool and moist. This type of air mass forms over the colder waters of the ocean in polar regions. As the air moves from the ocean, it picks up moisture, contributing to its humidity, while also being influenced by the cooler temperatures of the surrounding area.

Maritime polar air masses typically bring cloudy skies and precipitation when they move over land, especially when the temperature contrasts with the land, leading to instability and weather systems. This is especially evident in coastal areas where mP air masses frequently interact with warmer air.

The other options do not accurately describe the nature of mP air masses. Warm and moist conditions are characteristic of a maritime tropical (mT) air mass, while cold and dry would describe a continental polar (cP) air mass. Hot and dry conditions are associated with continental tropical (cT) air masses. Understanding these distinctions helps in predicting weather patterns associated with different air masses.