Context
The southwest monsoon is likely to be “normal” in 2022, though rainfall in August, the second rainiest month, will likely be subdued, according to the private weather company Skymet.
What are the Niño and La Niña?
- They are two natural climate phenomena occurring across the tropical Pacific Ocean and influence the weather conditions all over the world.
- While the El Niño period is characterised by warming or increased sea surface temperatures in the central and eastern tropical Pacific Ocean, a La Niña event causes the water in the eastern Pacific Ocean to be colder than usual.
- Together, they are called ENSO or El Niño-Southern Oscillation.
- After an El Niño event weather conditions usually return back to normal.
- However, in some years the trade winds can become extremely strong and an abnormal accumulation of cold water can occur in the central and eastern Pacific. This event is called a La Niña.
- A strong La Niña occurred in 1988 and scientists believe that it may have been responsible for the summer drought over central North America. During this period, the Atlantic Ocean has seen very active hurricane seasons in 1998 and 1999.
- One of the hurricanes that developed, named Mitch, was the strongest October hurricane ever to develop in about 100 years of record keeping
Causes of El Nino
- El Nino sets in when there is an anomaly in the pattern.
- The westward-blowing trade winds weaken along the Equator and due to changes in air pressure, the surface water moves eastwards to the coast of northern South America.
- The central and eastern Pacific regions warm up for over six months and result in an El Nino condition.
Effects of La Nina
- Some of the other weather effects of La Niña include
- abnormally heavy monsoons in India and Southeast Asia,
- cool and wet winter weather in southeastern Africa, wet weather in eastern Australia,
- cold winter in western Canada and northwestern United States,
- winter drought in the southern United States.
Normal Conditions
- Eastern Pacific == Coast of Peru and Ecuador == Cold Ocean Water == Good for Fishing.
- Western Pacific == Indonesia and Australia == Warm Ocean Water == Plenty of rains.
El Nino Condition
- Eastern Pacific == Coast of Peru and Ecuador == Warm Ocean Water == Fishing industry takes a hit.
- Western Pacific == Indonesia and Australia == Cold Ocean Water == Drought.
