Text:
In this video El Nino will be explained; a fluctuating weather pattern in the area around the equator in the Pacific. The full name of El Nino is ENSO: El Nino Southern Oscillation. Southern Oscillation means that there is a weather fluctuation in the Southern Hemisphere which is called El Nino. So to understand El Nino, we must first explain the normal weather pattern.
In a normal situation there is a high pressure area in the southeastern part of the Pacific Ocean. Here the wind turns counterclockwise and this wind takes cold seawater from the south to the equator. The trade winds from the east take this seawater to the west. This seawater heats up and is warm by the time it arrives at Indonesia. This creates a low pressure area, causing air to rise and rain.
On the west coast of South America, the seawater on the surface therefore moves to the west, promoting upwelling of cold water. This cold seawater creates cold, descending air, so a high-pressure area. Moreover, this water does not evaporate quickly, creating deserts in the west coast of South America.
In short; in the normal weather pattern, the west coast of South America is dry, due to the cold sea water, and the eastern area of Indonesia is very wet, due to the warm sea water.
Wind, air pressure and the temperature of the sea water reinforce each other. Suppose the wind decreases in strength. As a result, less warm seawater is blown towards the west. As a result, less cold ocean water rises in the eastern Pacific Ocean, making it less cold. As a result, the difference in temperature between the western part and the eastern part of the ocean decreases. As already explained, warm seawater creates a low pressure area and cold seawater creates a high pressure area. Because the difference in temperature of the seawater decreases, the difference in air pressure also decreases, so that the wind also becomes less strong.
Because the winds decrease, less water is moved westward again and the temperature difference between the eastern and western part of the Pacific decreases even more. In this way the wind, sea temperature and air pressure influence each other. Although it is not known where it exactly starts, it is clear that if either the wind, or the temperature of the seawater, or the air pressure change, the other two are also affected and the weather pattern changes.
El Nino occurs about every 2 to 7 years. The strength of the trade winds decreases, making the wind to the west less strong. As a result, the ocean water remains just west of South America and warms up there, up to a maximum of 6 degrees Celsius more than the normal temperature! This creates a low pressure area and precipitation falls in a normally dry area. Because there is hardly any vegetation in this area, because normally there is no precipitation, the rainwater is not retained and mudslides can occur. The warm ocean water contains much less fish. South American fishermen noticed that this frequently occurs around Christmas. They therefore called it El Nino, which is Spanish for "boy child", referring to the Christ child.
In the area around Indonesia, the seawater is colder than normal. As a result, the air pressure increases and less water evaporates. This makes it a lot drier than normal. Agriculture and fisheries are thus greatly affected in both areas.
If this situation continues for a long time, the warm seawater in the eastern Pacific Ocean will eventually flow north and south. Deeper seawater, which is cooler, can now resurface. As a result, the surface temperature in the eastern Pacific Ocean is getting colder and the weather is returning to the normal pattern.
Sometimes, however, the seawater cools above average in this area. This creates an extremely high pressure area, causing winds to the west to become stronger, more seawater to flow west, more deep, cold seawater to flow to the surface, creating a higher than normal temperature difference between the eastern and western Pacific. This will make it drier than normal in the eastern Pacific and even wetter than normal in the western Pacific. This opposite effect is called La Nina. This is Spanish for "girl" and thus the counterpart of El Nino, the boy.
El Nino affects not only the Pacific around the equator, but many more areas! The warm sea in the eastern Pacific Ocean creates heat and water vapor in the atmosphere, which can increase rainfall and flooding in many places in the world, such as in Peru and Ecuador. Also in the southern part of the United States, such as in California, it usually rains more after an El Nino.
At the same time, it is much drier in other places in the world, such as Indonesia, India, Southern Africa and Australia. The drought can cause forest fires or crop failures. This can cause food prices to rise and famine, which in turn can have political consequences.