The division of meteorology in ancient times was different from that in modern times

The difference between the division of meteorology in ancient times and modern times

This article discusses the differences between the division of meteorology in ancient times and modern times. Our country has a vast land, abundant resources, and diverse weather conditions. Many people are curious about the differences between ancient weather divisions and modern weather divisions. How were weather conditions and seasons divided in ancient times? Why did the meteorological divisions in ancient times differ from those in modern times? The division of meteorology in ancient times is different from that in modern times 1

Two points should be explained here. One is that in the era described in the "Huangdi Neijing", people's life activities were centered on the Yellow River Basin. One year The distinction between the four seasons is still different from that in most parts of my country. Here we will introduce the meteorological distinction between the four seasons so that everyone can have a comprehensive understanding of the four seasons.

From a meteorological point of view, there are several ways to divide the four seasons:

1. Astronomical division method

From the perspective of astronomical phenomena, the changes in the four seasons are: Seasonal changes in day and night length and sun altitude. In a year, the season with the longest days and the highest sun altitude is summer, the season with the shortest days and the lowest sun altitude is winter, and the transition seasons between winter and summer are spring and autumn. For this reason, the astronomical method of dividing the four seasons is to use the spring equinox (March 21), summer solstice (June 21), autumnal equinox (September 21), and winter solstice (December 21) as the beginning of the four seasons.

That is: spring is from the vernal equinox to the summer solstice, summer is from the summer solstice to autumn, autumn is from the autumnal equinox to winter solstice, and winter is from winter solstice to spring.

2. Meteorological classification method

In the meteorological department, spring is usually from March to May, summer is from June to August, autumn is from September to November, and autumn is from December to February of the coming year is winter, and January, April, July, and October are often regarded as the representative months of winter, spring, summer, and autumn.

3. Ancient division method

The beginning of spring (February 4 or 5) is the beginning of spring, the beginning of summer (May 5 or 6) is the beginning of summer, and the beginning of autumn ( August 7 or 8) is the beginning of autumn, and Beginning of Winter (November 8 or 9) is the beginning of winter.

4. Lunar calendar division method

It is customary for Chinese folk to use lunar months to divide the four seasons. The months from January to March of the lunar calendar each year are spring, the months from April to June are summer, the months from July to September are autumn, and the months from October to December are winter. The first day of the first lunar month is the first day of the whole year and the first day of spring, so it is also called the Spring Festival.

Although the above methods are simple and convenient, they have a common disadvantage, that is, all parts of the country enter the same season on the same day, which is very different from the actual situation in various regions of our country. of. For example, according to the above division method, March is already spring. At this time, the area south of the Yangtze River is indeed full of pink and willows, and the feeling of spring is strong; but in the north of Heilongjiang, it is cold, windy, icy and snowy, and there is no spring feeling at all; people on Hainan Island Then I have spent the summer wearing single clothes. In order to make the division of the four seasons consistent with the natural sceneries of various places and the rhythm of people's lives, the meteorological department has adopted the method of dividing the four seasons by temperature and temperature.

5. Temperature division method

This division method uses the average temperature of a pentad (five days as a pentad) as the temperature index to divide the four seasons. Summer begins when the zonal average temperature stabilizes above 22°C, winter begins when the zonal average temperature stabilizes below 10°C, and spring and autumn begin when the zonal average temperature ranges from 10 to 22°C. The rise from 10℃ to 22℃ is spring, and the fall from 22℃ to 10℃ is autumn. The division of meteorology in ancient times is different from that in modern times 2

The time scales of climate change include geological periods, historical periods, and modern climate, and small ones include interannual changes, decades, and hundreds of years. The causes of climate change are different in different periods.

Climate changes last the longest and have the greatest differences during the geological period. When the earth is at its warmest, there is no ice or snow at the poles all year round. At its coldest, it is almost entirely covered with ice and snow. The main causes of climate change in geological periods are plate movement, continental drift, orogeny, plateau uplift, and dramatic changes in atmospheric composition.

The main causes of climate change in historical periods include: solar radiation, internal factors of the earth, CO2 concentration, methane concentration, ozone layer, vegetation conditions, polar ice and snow conditions, etc.

Solar radiation may vary by about 2%. The internal factors of the earth are also very complex. Geological changes, volcanic activity, etc. will all affect the climate. Greenhouse gases (CO2, methane, etc.) and other factors are important factors affecting the earth's heat balance. Modern human activities have caused a sharp increase in greenhouse gases. The changes in greenhouse gases in historical periods are not as great as in modern times, but there are also fluctuations, mainly due to changes in the earth's internal emissions and changes in the biosphere. The impact of forests and vegetation on climate is generally a positive cycle. The more forests there are, the warmer and wetter the climate is and the more favorable it is for forests. On the contrary, it is a vicious circle. The influence of polar ice and snow is also a positive cycle. The more ice and snow there is, the more solar radiation is reflected and the colder the climate.

In the past four or five thousand years, China's climate has experienced three major warm and humid periods.

The first warm and humid period (about 3000aD,C,~1000aD,C,)

The second warm and humid period (770aD,C,~early AD).

The third warm period (600aA, D, ~ 1000aA, D,),

In recent thousands of years, although my country's climate has shown a periodicity on a time scale of hundreds of years, Cold and warm periods fluctuate, but the general trend is that the warm period continues to shorten, the cold period becomes longer and longer, and the degree of cooling in the cold period gradually increases.

The characteristics of China's monsoon climate are that warmth and humidity occur at the same time, and cold and drought occur at the same time. The main reason is that when the climate is warm, it is greatly affected by the subtropical atmospheric circulation system, resulting in more precipitation. At the same time, the temperature is high and the water vapor content in the atmosphere is also high. When the climate is cold, it is greatly affected by the westerly circulation system and receives less precipitation.

The main cause of global climate warming in the past few hundred years, especially the past hundred years, is the sharp increase in the concentration of greenhouse gas CO2. Numerical simulations of the climate system show that as the climate warms, the water cycle accelerates, and weather and climate extreme events increase and become more intense. Meteorological disasters are stronger and more frequent. The direct impact on humans is sea level rise, many areas at low latitudes will be submerged, and humans will lose their homes. There is also the impact and destruction of agriculture and natural ecosystems. Then there are intensified floods, droughts and other meteorological disasters.

As the climate warms, the temperature rises, and the moisture content of the atmosphere increases. Although evaporation increases, the overall moisture content of the atmosphere increases. However, accelerating the water cycle does not mean that precipitation will increase. As extreme weather events increase, droughts in some areas will become more severe when floods occur in some areas.

Whether the current climate change in northern my country will return to the warm and humid climate in the ancient north is still unclear due to the time scale. In other words, it awaits longer historical observation.