제 17 호 Solar Term: Wisdom of Life
Kicker: SCIENCE
Solar Term: Wisdom of Life
By Da-Hwee Kim, Editor-in-chief
Have you ever heard about the 24 solar terms in your daily life? Maybe today's younger generation may be less familiar with this concept than the older generation. Still, if you take a good look at the main image of the portal site that you frequently visit or watch the news with attention, I think you probably would know about this. In fact, surprisingly, the 24 solar terms come back twice a month every year! Isn’t it interesting? Therefore, this article would cover some of the great scientific facts along with the life wisdom related to solar terms.
What is the solar term?
The 24 solar terms were named according to the weather conditions in North China during the Zhou Dynasty. It was created to distinguish the seasons according to the position of the sun on the ecliptic. A total of 24 solar terms are represented by points at 15° intervals from the vernal equinox on the ecliptic*. In 2016, its value was recognized so it was listed as a UNESCO Intangible Cultural Heritage of Humanity.
* ecliptic: the orbital plane of Earth around the Sun
Solar calendar vs. Lunar calendar
There are concepts that need to be looked at for a while before looking into the scientific facts related to the 24 solar terms in earnest. It's the ‘Solar calendar’ and the 'Lunar calendar'. Let's take a quick look at them first.
The solar calendar is a method of counting days by setting the time it takes for the earth to go around the sun once a year. That is why it is often referred to as the ‘solar calendar’. The date we usually talk about in everyday life is the solar calendar. The Gregorian calendar has 365 days in a year, and leap years of 366 days every four years. Since the Earth's orbital period is not exactly 365 days, this is to set the time by adding an extra day.
The lunar calendar is a method of counting days based on the cycle of the moon's phase. The lunar calendar is often written in very small letters in the calendar we see. In the lunar calendar, a cycle in which the moon gradually grows larger to become a full moon and then smaller again is considered a month.
Scientific facts about the 24 solar terms
Considering that days were counted using the lunar calendar in the past, it is easy to think that the 24 solar terms are also the lunar calendar, but actually, it is not. In fact, looking at the calendar, the 24 solar terms occur between the 4th, 8th, 19th, and 23rd of every month, which corresponds to the solar calendar.
The arrangement of the 24 solar terms is divided into spring, summer, autumn, and winter. Each season is further divided into 6 equal parts so that two solar terms are arranged in a month based on the solar calendar. As it was based on the position of the sun, it is naturally related to the climate or the season. The climate varies from region to region because not only the movement of the sun but also various factors such as atmospheric flow are involved.
Names of all 24 solar terms
The seasons are determined according to the movement of the sun, For this reason, they come back on the same day every year, or sometimes with a difference of one day. The 24 solar terms for each season are as follows:
Spring | Summer | Autumn | Winter |
Start of Spring | Start of Summer | Start of Autumn | Start of Winter |
Rain Water | Grain Full | Limit of Heat | Minor Snow |
Awakening of Insects | Grain in Ear | White Dew | Major Snow |
Vernal Equinox | Summer Solstice | Autumnal Equinox | Winter Solstice |
Clear and Bright | Minor Heat | Cold Dew | Minor Cold |
Grain Rain | Major Heat | Frost Descent | Major Cold |
Limitations of the 24 solar terms in Korea
To tell the truth, since the 24 solar terms were not invented domestically, it was difficult for the name or climate to fit perfectly in Korea. For example, the ‘Minor Cold’ is way colder than the ‘Major Cold’. There is even an old proverb that says, 'There are people who freeze to death in 'Minor Cold', but no one freezes to death in 'Major Cold'." Just looking at the name, ‘Major Cold’ deserves to be colder, nevertheless, the case of Korea is an exception. This is because the cold in Korea usually starts at the ‘Start of Winter’ and becomes the coldest in ‘Minor Cold’. Therefore, during the reign of King Sejong in the Joseon Dynasty, it is said that he tried to supplement this point by compiling the Nongsakjikseol.Even so, it was difficult to completely solve the limitations.
In addition, the ongoing global warming problem is also playing a role. With the development of human civilization, the problem of climate change is becoming increasingly serious. As a result, abnormal temperature phenomena have followed one after another, and the 24 solar terms do not fit perfectly in our country.
Anyhow, isn't it surprising that people in the past lived by applying this amazing fact to their lives? It is true that the fact that the concept of solar terms does not fit perfectly for us nowadays since we are living in a modernized society that is not fully based on an agricultural society. Even so, if there are 24 solar terms in the news or weather forecast for the future, I hope you pay attention to them.
Sources :
https://www.doopedia.co.kr/doopedia/master/master.do?_method=view&MAS_IDX=101013000741034
https://terms.naver.com/entry.naver?docId=1529167&cid=47340&categoryId=47340
https://terms.naver.com/entry.naver?docId=6197311&cid=66877&categoryId=66877