i want a economies best bookEL Nino
El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Niña, which characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe. This is described as warmer-than-normal sea surface temperatures in the same area of the Pacific Ocean.
·El Nino means "Little Boy" and was named after the Christ child, because it usually starts around Christmas.
· El Nino is officially called ENSO - El Nino Southern Oscillation.
· El Nino may be caused by underwater volcanoes in the Pacific.
How Does El Nino Work?
In normal years, winds tend to blow from east to west across the waters of the tropical Pacific. The easterly winds (remember that wind directions refer to the direction FROM which the wind comes: an easterly trade wind comes from the EAST and blows WEST) push the surface waters westward across the ocean. In turn, this causes deeper, colder waters to rise to the surface. This "upwelling" of deep ocean waters brings with it nutrients that otherwise would remain near the bottom. Fish populations living in the upper waters are dependent on these nutrients for survival.
The consequent warming of the ocean surface further weakens the winds and strengthens El Niño. As the Pacific continues to heat up, the warmer waters shift eastward, and so do the clouds and thunderstorms that produce heavy rainfall along the equator. This results in changes in jet streams (the winds high aloft), which lead to dry conditions in Indonesia and Australia, and floods in Peru and Ecuador. El Niño events occur on average every 3 to 5 years, though there can be periods of up to a decade without an El Niño.
What Causes El Nino ?
The easterly trade winds become weaker, and can even reverse direction. The warm Pacific Ocean becomes nearly stationary or pushes eastward and gains heat. Besides affecting weather, El Nino has also been known to hurt fishing off the coast of Peru. El Nino lasts roughly an year
LA Nina
La Nina is described as cooler-than-normal sea surface temperatures in the central and eastern Pacific Ocean, near the equator off the west coast of South America. El Niño's twin sister is La Niña ("the little girl" in Spanish). Her effects are, as any siblings would expect, the exact opposite of El Niño's: for instance, precipitation is below normal in California and the southeastern U.S.! La Niña is characterized by below-normal sea surface temperatures in the eastern equatorial Pacific. There are large variations in weather for many U.S. locations from warm spells to cold waves during a La Niña winter.
What Causes La Nina ?
Simply put, easterly trade winds over the equatorial Pacific Ocean are partly to blame for both phenomenon. For La Nina, the easterly trade winds strengthen. This blows more warm water west, and allows cold water below the ocean's surface to push towards the top near the South American coast to replace the warm water.
Typically a La Nina lasts 9 to 12 months. As for this year's La Nina, forecast models are indicating slight strengthening through October and then a steady period in November and December. All of the models have the La Nina weakening throughout the spring and early summer.
IDL
The International Date Line (IDL) is an imaginary line on the surface of the Earth, that runs from the north to the south pole and that demarcates one calendar day from the next. It passes through the middle of the Pacific Ocean, its path roughly following the 180° longitude. However, it deviates to pass around some territories and island groups. It generally follows the 180° meridian of longitude, where, by international agreement, travelers change dates. Traveling eastward across the line, one subtracts one calendar day; traveling westward, one adds a day. The date line is necessary to avoid a confusion that would otherwise result. For example, if an airplane were to travel westward with the sun, 24 hr would elapse as it circled the globe, but it would still be the same day for those in the airplane while it would be one day later for those on the ground below them. The international date line does not follow the 180° meridian along its entire course but bends eastward around the eastern tip of Siberia, westward around the Aleutian Islands, and eastward again around various island groups in the South Pacific in order to avoid a time change in populated areas.
