Explanation:

• El Nino means ‘little boy’ or ‘Christ child’ in Spanish because it was first recognised by South American fishermen in the early part of the 17th century. The events, i.e., warm waters in the Pacific Ocean, tended to occur in December, hence, the name was chosen.
• El Nino refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. It is associated with high pressure in the western Pacific. El Nino adversely impacts the Indian monsoons and hence, agriculture in India.
• La Nina means ‘little girl’ in Spanish and is also known as El Viejo or ‘cold event’. Here, the water temperature in the Eastern Pacific gets colder than normal. As a result of this, there is a strong high pressure over the eastern equatorial Pacific. Now, there is low pressure in the Western Pacific and off Asia.
• La Nina causes drought in Peru and Ecuador, heavy floods in Australia, high temperatures in Western Pacific, Indian Ocean, off the Somalian coast and good monsoon rains in India. A La Nina is actually beneficial for the Indian monsoon.
• Generally, El Nino and La Nina occur every 4 – 5 years. El Nino is more frequent than La Nina. Typically, the episodes last for nine to twelve months.