Answer:
The polar air mass and the Gulf of Mexico air mass
Step-by-step explanation:
The two air masses that have the greatest influence on the weather east of the Rocky Mountains in North America are the polar air mass and the warm, moist air mass from the Gulf of Mexico. The polar air mass is typically cold and dry, and can bring cold temperatures and clear skies to the region. The warm, moist air mass from the Gulf of Mexico is typically warmer and more humid, and can bring mild temperatures and precipitation to the region. These two air masses can interact and combine to produce a variety of weather conditions, including snowstorms, thunderstorms, and tornadoes. The specific type of weather that occurs in a given location can depend on a number of factors, including the time of year and the location's geography.