El-Nino develops in which of these oceans?

The correct answer is Pacific Ocean.

Key Points:

EL- NINO:

• El Nino (Spanish for Christ Child) is the occasional development of warm ocean surface waters along the coast of Ecuador and Peru in South America. 
• Even though El Nino occurs in the Pacific Ocean, it often reduces the number of hurricanes that form in the Atlantic Ocean. Conversely, La Niña events tend to be related to an increase in the number of Atlantic hurricanes.
• Recently this development has been used for forecasting climatic conditions in different parts of the world. 
• The El Nino normally occurs around Christmas, roughly every 2 to 7 years, and lasts usually for a few weeks to a few months. 
• El Nino event is related to two important atmospheric circulation systems:  
  • Hadley Circulation: It features air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth’s surface, descending in the subtropics, and then returning equatorward near the surface. 
  • Walker Circulation: There is a stable low-pressure system above the western Pacific near South East Asia and a high-pressure system in the central Pacific.
• This results in a constant westward flow of air masses from the area of high pressure to the area of low pressure. At higher altitudes, this air then flows directly eastward, oblique to the Hadley Circulation. 
• Due to the combined components of Walker Circulation and Hadley Circulation, there is a strong prevailing wind toward the west in the lower layers of the atmosphere, which maintains the stable coastal upwelling system off the coast in western South America. 
• El Nino and the Indian Monsoon rains are inversely related. 

​