Enso-cycle

El-Niño & La-Nina

Submitted to : Dr. shumyla Nawazish

Submitted by : Amad Maqsood

Content

El-NinoSign of El NinoThermocline & convention loopEffect of El NinoHistory of El NinoPrediction of El NinoCauses of El-Nino & La-Nina

El NiñoEl Niño and La Niña are opposite phases is known

as the El Niño-Southern Oscillation (ENSO) cycle. An irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every few years, characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.

ContinuedGenerally affects Northern Hemisphere in the

winterOriginates around equatorHistorically, it has occurred at irregular intervals of

2-7 years

Signs of an El NiñoA rise in air pressure in the Indian Ocean, Indonesia, and

AustraliaA fall in air pressure over Tahiti and the rest of the central

and eastern Pacific Ocean The trade winds in the South Pacific weaken or head eastWarm air rises in PeruWarm water spreads from the West Pacific and the Indian

Ocean to the East Pacific. It takes the rain with it, causing rainfall in normally dry areas and drought in normally wet areas.

What is thermocline?A layer within a body of water or air where the

temperature changes quickly with depth.

What is convective loop?A heating cycle often fueled by the sun in which a liquid

or gas within a closed system is heated and rises.

El Niño’s warm current of nutrient-poor tropical water replaces the cold, nutrient-rich surface water where Peru’s fishing industry usually is vibrant.

But it doesn’t stop there?

The warmer ocean then affects the winds, and makes the winds weaker. So if the winds get weaker, then the ocean gets warmer, which makes the winds get weaker.

This is called positive feedback, and it’s what makes El Niño grow.

The Effects of El Niño are Worldwide

Effect of El-Nino world wideWet winters over southeastern United States.Drought in Indonesia and Australia, and other places that are typically wet.

Flooding in South America in areas typically dryWildfires and mudslides.Warmer winters in the upper Midwest states and Canada.

History of El Nino

ENSO conditions seem to have occurred at every two to seven years for at least the past 300 years, but most of them have been weak.

Archaeological evidence in Peru that suggests it has occurred for thousands of years.

The El Niño of 1997 to 1998 was particularly strong and brought the phenomenon to worldwide attention.

How we predict El Nino?

Satellite readings from buoys strategically set in the Pacific Ocean.

Complex computer models.

El Niño vs. La Niña

El NiñoUnusually warm ocean temperatures in eastern Pacific.Usually more intense effects than La Niña.Summers in Omaha tend to be wetter and cooler.

La NiñaUnusually cold ocean temperatures in eastern Pacific.Usually follows El Niño, but not always.Summers in Omaha tend to be drier and warmer.

What the heck causes El Niño and La Niña?