EI-Nino is a complex weather system that appears once every three to ______ years, bringing drought, floods and other weather extremes to different parts of the world.

The correct answer is seven.

Key Points

• El Nino refers to the unusual warming of the central and east-central equatorial Pacific Ocean which affects global weather.
• The warmer waters of the Pacific Ocean cause the winds in various regions to reverse, like the trade winds that come towards India.
• It is a complex weather system that appears once every three to seven years, bringing drought, floods, and other weather extremes to different parts of the world.
• Over India, the El Nino has usually been the harbinger of drought and the La Nina of rain.​

Additional Information

• There is also an opposite of an El Nino, called La Nina means The Little Girl in Spanish.
• This refers to times when the waters of the tropical eastern Pacific are colder than normal and trade winds blow more strongly than usual.
• Collectively, El Nino and La Nina are parts of an oscillation in the ocean-atmosphere system called the El Nino-Southern Oscillation, or ENSO cycle.