At the beginning of March, many places have been liberated from the cold winter state in February, and the temperature has begun to rise rapidly, repeatedly refreshing the highest temperature this year.
Among them, the maximum temperature in many places in the south exceeded 20 °C, and the maximum temperature even reached 31.6 °C, and the day of spring and warm blossoms really came.
On the other hand, from the perspective of the highest temperature in the country alone, the temperature in Many places such as Yunnan, Fujian, Guangdong, and Hainan on the mainland has exceeded 28 °C. According to the "average weather temperature" method, when the average temperature of 5 days is higher than 22 °C, it is considered to have entered summer.
Is the maximum temperature in the 4 southern provinces so high that it really enters the summer?
summertime
In life, there are two ways to divide the summer, one is the 24 solar terms, every year from summer to autumn is summer, as long as the day comes, no matter how high the local temperature is, or how low it is counted as entering the summer. Judging from the division of the 24 solar terms, the four southern provinces of the mainland have not entered the summer.
However, this method of dividing the seasons is too simple and crude, to know that the geographical location of the continent is vast, spanning multiple latitudes, and there are multiple mountain ranges in the middle to block the cold and warm currents, as well as the difference in the region, dry and wet environment, resulting in different temperatures in different places at the same time, and even the gap is very large. The method of dividing the summer with 24 solar terms is difficult to apply to many places in the country.
Therefore, meteorology will adopt the "post-average temperature method", which stipulates that the average temperature of 5 consecutive days is less than 10 °C as winter; greater than 22 °C is summer, and between the two is spring and autumn.
From the perspective of the "average weather method", the average temperature of Jinghong in Yunnan from 2 to 5 days is 22.2 °C, and the average temperature of Mengla on the 2nd to 5 days is 22.5 °C, which has entered the summer.
However, the average temperature of the entire Yunnan Province in the next 5 days has not reached 22 °C, so Yunnan Province has not entered the summer. Similarly, although the maximum temperature in Fujian, Guangdong and some parts of Hainan is high, the average temperature in the next 5 days does not meet the summer standard of the "average temperature method" and has not entered the summer.
This time can only be regarded as a local area into the summer, and it will take a while to wait for many places in the south to really enter the summer.
Is spring really shortened?
Over the years, there have always been netizens on the Internet who joke that the spring and autumn seasons are getting shorter and shorter, and even many places only have two seasons left, winter and summer.
So the question is, is spring really shortened?
Judging by the 24 solar terms, spring in the Northern Hemisphere is indeed getting shorter every year, 30 seconds shorter each year, and 30 seconds longer in summer. In addition, the winter is getting shorter, and the autumn is getting longer and longer.
Scientists have deduced that at the age of 3,000, the northern hemisphere had only 91.97 days of spring, 93.92 days of summer, 90.61 days of autumn, and 88.74 days of winter.
Why do the winter and spring seasons become shorter, and the summer and autumn seasons slowly become longer?
This is actually related to the orbit of the Earth, the orbit of the Earth around the Sun, not a perfect circle, but an elliptical shape.
Among them, in early January of each year, the Earth is closest to the Sun, which is the perihelion; the farthest from the Sun in early July each year is called the Far Sun.
The faster the Earth moves at perihelion, the shorter the winter and spring seasons in the Northern Hemisphere, while at aphelion the Earth rotates slower, so summers become longer and longer.
It is only because the spring is shortened so slowly due to the rotation of the earth that it is difficult for human limited life to feel this change. But many netizens have felt that spring is getting shorter and shorter, so what is going on?
Spring is really getting shorter
In addition to the shortening of the spring time of the 24 solar terms, the spring time divided by the "average weathering method" is also getting shorter and shorter.
China Weather Network once counted the length of spring in Beijing in 10 years since the meteorological records were recorded in 1951, and the results of the study found that the average number of spring days was really getting shorter, from 1951 to 1960, the average number of spring days in Beijing was still 61 days, but from 2011 to 2017, there were only 50 days left, a total of 11 days less. No wonder the literati always say "spring neck is short".
It's not just that Spring has become shorter in Beijing, but according to meteorological data over the past 60 years, Spring in Shijiazhuang is also slowly shortening.
From 1958 to 1967, there were 569 days of spring, while from 2008 to 2017, there were only 557 days of spring.
The same situation has emerged in Shanghai, where spring is slowly getting shorter.
So what's really going on over the years, and why is spring getting shorter and shorter?
In fact, this matter has long been concerned by scientists, the Chinese Academy of Sciences and related laboratories researchers, using observation data from 1952 to 2011, statistics found that the average number of summer days increased from the past 78 days to 95 days, while the spring from 124 days to 115 days.
The reason behind this is global warming.
In the context of global warming, extreme weather occurs frequently, the number of summer high temperature days becomes longer and longer, and extreme heat becomes more extreme. In winter, the pressure gradient forces in the equatorial and polar regions are also reduced by global warming, making it easier for cold air to move south.
The researchers predict that if this trend continues without any measures taken to mitigate climate change, by 2100, the winter will last less than two months, the transitional spring and autumn season will be further shortened, and the summer will become longer and longer.