Ccold air is denser than warm air. when a cold air mass moves into a warm air mass, causing a cold a cold front, the warm air mass is a. squeezed downward, causing clouds and rain b. wedged upward, where its water vapor c. forced backward, as the approaching cold air replaces it d. compressed into a smaller mass, as it becomes even warmer which of these best explains the reason that thunderstorms are likely to form on a hot day? a. warm, humid air rises quickly and then cools b. as air slowly rises it loses humidity and causes rain c. the air is usually calm and allows the clouds to form d. the air rises quickly and forms low-level cloud layers