Continental polar (cP) continental arctic (cA) continental tropical (cT) maritime polar (mP) maritime tropical (mT) a. Air masses are warm and humid, and are responsible for the hot, muggy weather that frequently plague the eastern United States in summer. b. Air masses that are cold and dry and form over land. c. Air masses that are hot and dry, and are responsible for heat waves of summer in the western half of the United States. d. Air masses that are extremely cold and dry and form over land. e. Air masses that are cold and moist, form over water, and are responsible for the cold, damp, and often wet weather in the western United States.