Warm air masses are large bodies of air that have similar temperature and humidity characteristics. They typically form over warm regions, such as oceans or deserts, and can influence the weather in the areas they move into. These air masses are generally associated with clear skies and mild temperatures, making them important for pleasant weather conditions. When a warm air mass moves into a cooler area, it can lead to various weather phenomena, including cloud formation and precipitation. The interaction between warm and cold air masses is crucial in creating weather fronts, which can result in changes in temperature and stormy conditions.