How do mountain and valley breezes get their names?

Mountain and valley breezes are named for their respective origins in mountainous terrain. During the day, the sun heats the mountain slopes faster than the valleys, causing warm air to rise and creating a valley breeze that flows uphill. At night, the opposite occurs: the slopes cool more quickly than the valleys, causing cooler, denser air to flow down from the mountains, resulting in a mountain breeze. These breezes are named based on the direction of airflow relative to the terrain.