In addition to instabilities, oscillations occur in the atmosphere- ocean system. The strongest is known el ni o - southern oscillation. Occurs irregularly every 3-7 years, a result of complex air-sea interaction in the tropical pacific. During el ni o, a warm pool of surface waters in the western tropical pacific extends far to the east, to the peruvian coast. Displaces a normally rainy area from the west to central. Something that causes more of something else to happen. Something that causes less of something else to happen. Temperature and precipitation anomalies in the tropics and elsewhere. 1982-83 el ni o: thousands of deaths (floods, droughts, disease, ) and over billion worth of damages. Daily breezes: sea/lake and land; mountain and valley. The greatest seasonal change in earth"s global circulation is the development of monsoons, wind systems that exhibit a pronounced seasonal reversal in direction. The best known and most pronounced monsoonal circulation, the.