El-Nino is a global weather phenomenon. It occurs in the Eastern and Central Pacific ocean. Due to this, the seasonal monsoons get disturbed and natural disasters like droughts and floods take place.
First I'll explain the normal conditions in the Pacific region and then explain the El-nino effect.
Normal Conditions: The process takes place between the oceans and the atmosphere. Winds flow from East to West from the surface of the water. Surface waters of ocean are very warm and the water under oceanic beds is cold and contains various types of nutrients which is helpful for aquatic life and to the soil when it reaches the land through rains. So, when the wind flows from East-West, the it displaces the surface water to the west side causing the cold water to move upward. There is a divide called "Thermocline" that divides the warm waters from the cold water. Due to the displacement of the water thermocline moves up to the Eastward. And the warm water will be collected in the western side and then moves into the atmosphere. This process repeats which is the process for rainfall occur.
El-Nino conditions: Now what happens when El-Nino condition occurs is, eastern winds become weaker resulting in carrying of little amounts of water to western side. As a result, the surface warm waters remain in the same position and cold water circulation will not come into act. And therefore, the thermocline is flat resulting in warming the atmosphere and shortage of rainfall. This is the position where the monsoons are effected.
Note: Date Line mentioned in the diagram is the longitudinal line that passes through the center of the Pacific ocean. This is the longitudinal line that is opposite to 0 degrees longitude.
Reference:airsea-www.jpl.nasa.gov
Normal Conditions: The process takes place between the oceans and the atmosphere. Winds flow from East to West from the surface of the water. Surface waters of ocean are very warm and the water under oceanic beds is cold and contains various types of nutrients which is helpful for aquatic life and to the soil when it reaches the land through rains. So, when the wind flows from East-West, the it displaces the surface water to the west side causing the cold water to move upward. There is a divide called "Thermocline" that divides the warm waters from the cold water. Due to the displacement of the water thermocline moves up to the Eastward. And the warm water will be collected in the western side and then moves into the atmosphere. This process repeats which is the process for rainfall occur.
El-Nino conditions: Now what happens when El-Nino condition occurs is, eastern winds become weaker resulting in carrying of little amounts of water to western side. As a result, the surface warm waters remain in the same position and cold water circulation will not come into act. And therefore, the thermocline is flat resulting in warming the atmosphere and shortage of rainfall. This is the position where the monsoons are effected.
Note: Date Line mentioned in the diagram is the longitudinal line that passes through the center of the Pacific ocean. This is the longitudinal line that is opposite to 0 degrees longitude.
Reference:airsea-www.jpl.nasa.gov
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