Scientists say that the world is warming, so why is there a double-peak La Nina phenomenon?

Global warming and La Nina are two completely different concepts, but under their joint action, extreme climate will appear all over the world, and winter in China will become colder!

According to the latest news from the National Meteorological Center, since July 20021year, the sea water in the eastern Pacific near the equator has been unusually cold, and La Nina phenomenon was formed in June 20021year. It is predicted that China will experience a weak to moderate La Nina event in winter.

At this time in 2020, La Nina phenomenon also formed, and it didn't end until March 20021year. That is to say, China experienced La Nina twice in 202 1 year, which is the so-called "double peak La Nina", which is relatively rare in history.

Then the question is, will La Nina with two peaks cause the cold winter of 20021year in our country? Why does it feel colder and colder in winter in the context of global warming? Let's look at the answers to these two questions.

1, what is La Nina phenomenon? La Nina refers to the abnormal cooling of seawater in the central and eastern Pacific Ocean. This definition is relatively simple, and it is hard to see that La Nina will affect global climate change. Explain it in detail below.

Generally speaking, under the influence of the southeast trade winds in the Pacific Ocean near the equator, the seawater heated by the sun on the surface of the eastern Pacific Ocean will be blown to the western Pacific Ocean by the trade winds, and then the cold seawater at the bottom of the eastern Pacific Ocean will turn up to supplement the blown seawater.

This is a very normal climate phenomenon. Warm seawater blown to the western Pacific will raise the temperature above the sea surface and reduce the air pressure. These moist air will eventually accumulate to form typhoons or tropical storms. Most typhoons in summer and autumn in China are generated in this way.

However, in some years, the intensity of the southeast wind is extremely strong, which makes more seawater from the eastern Pacific be blown to the western Pacific, so that there will be more cold water from the bottom of the eastern Pacific and the temperature will be lower, which in turn leads to a lower temperature over the eastern Pacific.

At this time, because there are more warm currents in the western Pacific than in previous years, the temperature over the region will be higher, so the wind force blowing from the eastern Pacific to the western Pacific will be strengthened, forming some positive cycles.

When the SST in the East Pacific Ocean is lower than the annual average of 0.5℃ for 6 months, La Nina phenomenon is formed, which will lead to a series of climate changes.

So La Nina is the product of the interaction between tropical ocean and atmosphere. After the formation of La Nina, typhoons or tropical storms in the western Pacific will be more intense in summer and autumn, and the cold high pressure in the Arctic will go south more easily in winter and spring, which means that La Nina will cause more extreme climate change.

2. It is obviously global warming. Why is it getting colder and colder in winter? From 1 1.4, China will usher in a national cold wave, which is characterized by wide influence range, long duration, large cooling range and strong rain and snow weather.

In most parts of China, the temperature drop can reach 8 ~ 10℃, and in some parts of the north, the temperature drop can reach 12 ~ 14℃, and even the extreme situation of 16℃ appears. Like this cold wave, China has experienced several times in the winter of 2020. Didn't we agree on global warming? Why do we feel that winter is getting colder and colder?

In fact, this is just a human feeling. For example, the sudden drop in temperature caused by this cold wave will obviously make people feel very cold. This is because before the arrival of the cold wave, the temperature in most parts of China was relatively high and impressive, but it is unknown whether the average temperature in winter in 20021year really dropped.

For example, in the winter of 2020, China experienced four cold waves, and people obviously felt the cold winter and called for "freezing and crying", but in fact, the average temperature in the winter of 2020 in China was slightly higher than the average, which was a real warm winter.

If the time is prolonged, the general trend of the average winter temperature in China is from 196 1 to 20 19, and the increase range is about 3℃, which means that the winter in China was much colder than now decades ago.

In fact, this cold wave is related to global warming. The specific explanations are as follows: First, most of the land on the earth is concentrated in the northern hemisphere, and the cold air in the northern hemisphere mainly comes from the Arctic.

When there is still 6.5438+0.5 million square kilometers of ice in the Arctic, a cyclone will form on the ice, making the cold air spin in the same place. When there is only120,000 square kilometers of ice in the Arctic, a large amount of cold air originally circulating in the same place will flow to the south with the global atmosphere, making the continent outside the polar regions even colder in winter.

Therefore, for a long time, the global climate is getting warmer and warmer, but in a short time, people feel that winter is getting colder and colder, which is actually an illusion left by extreme climate, and this short-term fluctuation can not affect the overall trend of global warming.

3. Will La Nina with Twin Peaks bring winter to China? Finally, let's look at a question that everyone is concerned about, that is, under the influence of La Nina, will there be a cold winter in the winter of China 202 1? Say the answer first: not necessarily!

Look at the definition of cold winter, and you will understand that cold winter refers to the winter in which the average temperature of the whole winter is 2 degrees Celsius lower than the average of the winter in recent 30 years.

You may say that the difference of 2℃ will not have obvious proper limit, which is true, but this is the average temperature. The difference of 2℃ is likely to be the overall cooling caused by local areas in a short time, so it will obviously feel extremely cold weather.

Let's talk about La Nina. Of the five La Nina years from 196 1 to 2020, only 10 is a cold winter, and the other five La Nina years are warm winters. In other words, La Nina does increase the probability of a cold winter in China, but La Nina cannot be equated with a cold winter.

Take the winter of 2020 as an example. Under the influence of La Nina, there were four cold waves in China, but the winter in 2020 was finally determined to be warm, because there was a nationwide warming weather in February 20021year near the end of winter, which suddenly raised the average temperature.

In a word, La Nina will make the winter temperature in our country colder, and even extreme low temperature will appear. It's not impossible to freeze to death and cry, but it's too early to say it's a cold winter.

4. Conclusion The strongest cold wave is coming. The double influence of global warming and La Nina phenomenon caused this cold wave, and the nationwide cooling is inevitable.

However, there will be no extreme cold in late autumn, so don't worry too much. As long as we always pay attention to the weather changes, it is beneficial to prepare for the cold in advance to prevent the sudden drop of temperature from causing a cold.