Why is the weather changeable these days?

El Nino warm current is an abnormal natural phenomenon in the Pacific Ocean, and it is a famous Peruvian cold current flowing from south to north on the west coast of South America and the eastern part of the South Pacific. Every June 1 1 to March of the following year is the summer in the southern hemisphere. The water temperature in the southern hemisphere generally rises, and the equatorial warm current flowing eastward strengthens. At this time, the global pressure belt and wind belt move south, and the northeast trade wind passes through the equator and is deflected to the left by the self-deflection force (also called rotational deflection force) in the southern hemisphere to enter the northwest monsoon. The northwest monsoon not only weakens the southeast trade wind, which is near the west coast of Peru, but also weakens or even disappears the cold water flooding of Peru's cold current. It also blows the equatorial warm current with higher water temperature to the south, which makes the water temperature of Peru's cold current abnormally rise. This quiet and unstable ocean current is called "El Nino Warm Current".

The word El Nino comes from Spanish El Nino? O, which means "little boy" or "little girl", also refers to the baby, that is, Jesus. It is used to indicate that the sea surface temperature on the west coast of South America (near Peru and Ecuador) extends westward and reaches the international international date line through the equatorial Pacific Ocean.

In normal years, trade winds prevail in the southeast of this area. The easterly stress on the equatorial surface transports surface warm water to the western Pacific Ocean and accumulates there, which leads to the rise of sea level and seawater temperature there. In the East Pacific Ocean, under the action of the near sea breeze, the surface seawater drifts offshore, which leads to the continuous divergence of seawater quality, the decline of sea level and the upwelling of cold water in the lower layer, which leads to the decrease of sea surface temperature here. The upwelling cold seawater is rich in nutrients, which makes plankton multiply and provides sufficient bait for fish. The prosperity of fish provides abundant food for fish-eating birds, so there are many birds here. Because the seawater temperature is low, the water temperature is lower than the air temperature, and the air stratification is stable, convection is not suitable for development. The equatorial eastern Pacific has little rainfall and a dry climate. However, due to the high seawater temperature, unstable air stratification, strong convection, more precipitation and humid climate in the equatorial western Pacific Ocean.

When the southeast wind is unusually strong, the upwelling of seawater in the equatorial eastern Pacific Ocean is extremely strong and the precipitation is extremely low. In the equatorial western Pacific, however, the seawater temperature is unusually high and the precipitation is unusually high. This is the so-called La Nina incident. La Nina phenomenon, contrary to El Ni? o, refers to the abnormal decrease of seawater temperature in the eastern Pacific Ocean. Both of these phenomena are closely related to the global climate, which may lead to an increase in the probability of extreme weather.

However, every few years, the southeast trade winds weaken, the cold water upwelling in the eastern Pacific disappears, and the surface warm water moves eastward, which leads to the rise of the equatorial eastern Pacific and the rise of the sea surface water temperature, and the coastal areas of Peru and Ecuador change from cold ocean currents to warm ocean currents. Inorganic salts in the lower seawater no longer washed up on the water surface, resulting in a large number of local plankton and fish deaths, and a large number of birds also died of hunger. Form a serious disaster. At the same time, the original dry climate has turned into a rainy climate, and even caused floods. This is El Nino.

El Nino's impact on climate is most significant in the equatorial Pacific. In the El Nino year, Indonesia, Australia, the South Asian subcontinent and northeastern Brazil all experienced drought, while it was rainy from the equatorial central Pacific to the west coast of South America. El Nino will bring devastating effects, which may lead to floods in Latin America, droughts in Australia and crop failures in India. Many observation facts also show that El Nino events have a certain influence on the circulation changes in quite far areas and even in the middle and high latitudes of the northern hemisphere through the teleconnection of air-sea interaction. It is found that when El Nino appears, it will cause continuous low temperature in summer in Japanese archipelago and northeast China, and precipitation tends to be less in most parts of China in some years. This shows the integrity of the earth's surface environment from one side: the change of one sphere will lead to the change of other spheres, the change of one region will lead to the change of other regions, and the local change will also lead to the change of the hemisphere and even the global environment.