Mountain and valley breezes are periodic winds formed due to variation in gravity. They are formed in the mountain slopes.
(а) Mountain Breezes : They occur during nights when the air at upper slopes becomes dense, compressed and heavy due to more cooling and ground radiation. At the same time lower slopes are relatively warmer and have low pressure. Now heavy air descends, it is termed as mountain breeze or gravity winds.
(b) Valley Breezes : They occur during the day time. Due to insolation, valley bottom gets heated, air becomes light and it ascends upslopes. It is termed as valley breeze.
Mountain Valley Breezes.
