El Nino And La Nina Weather Essay

, Research Paper

Before venturing to El Nino, a little background on scientific studies tracking this event are in order. Leonardo DaVinci compared oceans to air movement in the 16th century. From his comparisons, scientists started looking at the oceans in order to understand the atmosphere. What they found were eddy currents/eddy fields these are found near ocean currents and are swirling water caused by the jet stream. A spinning eddy in the sea has been compared to a tornado in the atmosphere. From these and other studies, it was realized the ocean clearly drives the atmosphere (Blue Planet). Weather was tracked in the 17th century by the Royal Society of London and the Academia del Cimento of Florence, Italy (Boeson 14).

Because life on earth is shaped by its climate and the earth s climate changes as dramatically as the atmosphere, Man can ascertain climate from the past by observing the sea and soil. Climate cycles last 100,000 years, where the first half is colder and the second, warmer. Inside these are sub-cycles lasting 20,000 years; it has been noted that all cold places have been warm, all wet, dry, and vice versa. Scientists are studying how seawater and air are partners, mirror images of each other. Additionally, because the ocean is more dense than the atmosphere, scientists study it because it has memory and can predict what will happen in the air, creating as it were, a duet and counterpoint of sea and sky (Blue Planet).

El Nino has been recorded for over 2,000 years and is so-named because fisherman noticed the waters off Peru warming near Christmas. El Nino means little boy or Christ child . It has been observed to happen every two to seven years. (For some reason, every few years, the current is stronger and warmer than usual). El Nino is warm water coming north and mixing with the Humboldt Current. It is a complex interaction between ocean and atmosphere, a chain reaction with far-reaching effects on worldwide weather and economy (Facklam 42).

Scientifically, El Nino is known as ENSO, El Nino Southern Oscillation (Facklam 46). Herbert Boomerang Walker, a British meteorologist coined the term southern oscillation in 1928 when he developed a theory about high pressure in the Pacific Ocean causing low pressure in the Indian Ocean. He noticed when this occurred, India had monsoons, Africa had rain and Canada experienced above normal temperatures (Facklam 49). Presently, scientists have called this phenomenon a teleconnection because it affects weather in other parts of the world. Weather is the result of a worldwide swirl of energy, and changes in climate can cut across political and economic boundaries.

Sun, rain, wind and sea are linked as they circle the globe. The sun heats low lying air in the tropics, which rises. Colder, heavier air over the north and south poles flows toward the equator. In the Northern Hemisphere, air is forced to the right (clockwise), while in the Southern Hemisphere, air twists left (counter clockwise). The winds created by these events are known as the trade winds (Gold 19).

Near the equator, general air circulation consists of a north-south cell also known as the Hadley Cell. Near the equator, large-scale convection causes air to rise into the upper troposphere, where it flows pole-ward. (The atmosphere is a kind of heat engine that extracts energy from a warm source (equator) and deposits the unused energy at a cold sink (the poles). This is how the general atmospheric circulation works (www.sciam.com), and helps one to understand El Nino s worldwide effects on weather.

Also included in this mix is the jet stream, which is a narrow band, 25,000 – 35,000 feet above the earth along which high-speed winds blow from west to east, affecting weather from North America to Africa and Asia. In the winter, the jet stream can travel more than 600mph (Falklam 6).

Normally, strong trade winds on the ocean s surface drive currents west in the equatorial Pacific, causing cold water from the deep ocean to rise to the surface, bringing nutrient-rich food for marine life. These westward-blowing winds trap warm ocean water along Australia and Indonesia. During El Nino, the winds relax and water flows downhill, across the ocean eastward to Peru and Ecuador. Sometimes the winds reverse direction and speed the warm water eastward. When this happens, a huge underwater mass called a Kelvin Wave is formed. This giant wave travels east at five knots (5.8 mph), covering 125 miles a day. Spread out across 6,000 miles (9,655 km), this El Nino has more force than one million atomic bombs enough to heat an ocean of water the size of Canada (Gold 23).

When the trade winds push the warm top layer of ocean away from the west coast of South America towards the coasts of Australia and Indonesia, this raises the ocean level in the western Pacific about + meter higher in Australia and Indonesia than in Peru. As this reversal of sea and air pressure occurs, El Nino emerges.

El Nino itself doesn t create rain, snow, ice or drought; it sets the stage for this weather to occur (Gold 25). Warm water heats the air above it affecting air pressure, sea level and the winds that blow across the Pacific, which affects weather, causing rains in dry areas and droughts in those usually humid (Gold 14). This area can be so large and deep in the atmosphere that upper air wind currents are affected. B