A year cut into twenty-four pieces
The twenty-four solar terms (jieqi) divide the year into periods of about fifteen days each. They are based on the position of the sun, not the phase of the moon, which means they come around on nearly the same Gregorian date each year, usually shifting by no more than a day. This makes them a steady backbone beneath the moving dates of the lunar calendar, which is why the traditional system is called a lunisolar calendar. Their main job was practical: telling people when to sow, weed, harvest and prepare, in a country where farming set the rhythm of life.
The system is usually said to have developed in the Yellow River region of northern China, where the climate and crops shaped the names. Its basic structure appears in texts from the Han dynasty. The practice was added to UNESCO’s list of intangible cultural heritage in 2016. Because the names reflect conditions in the north, they fit other regions less exactly, and southern and western farmers adapted the idea to their own climates.
The names
Each year starts for this purpose with the Start of Spring, around February 4. The terms, in order, are:
- Spring: Start of Spring, Rain Water, Awakening of Insects, Spring Equinox, Clear Brightness, Grain Rain.
- Summer: Start of Summer, Grain Buds, Grain in Ear, Summer Solstice, Minor Heat, Major Heat.
- Fall: Start of Fall, End of Heat, White Dew, Fall Equinox, Cold Dew, Frost Descent.
- Winter: Start of Winter, Minor Snow, Major Snow, Winter Solstice, Minor Cold, Major Cold.
That makes four seasons of six terms each, twenty-four in all. “Clear Brightness” is Qingming, the spring day of remembering ancestors. Some of the names are about weather (rain, dew, frost, heat and cold), some about nature (insects waking), and some about crops (grain buds, grain in ear). The solstices and equinoxes are the astronomical anchors, and the “start of” terms mark the traditional beginning of each season, which is earlier than the astronomical seasons used in the West.
Major and minor terms
Terms alternate between two types in the traditional system: “jie” (nodes) and “qi” (the central or principal ones). The principal ones include the equinoxes and solstices. This distinction matters because the placement of a leap month depends on a month with no principal term. The solar terms therefore help keep the lunar months aligned with the seasons.
Sayings and rhyming rules
Because the terms were so useful, rural communities developed short sayings, rhymes and proverbs around them. Many are about timing: when to plant, when frost may return, when rain is likely. For example, there are well-known rhymes that link the term “Grain in Ear” to the busy period of harvesting and sowing, and a general feeling that one should not miss the timing of the terms. Such sayings vary by region and are folk observations, not scientific rules, and they do not always match the weather in a given year. They belong to the same tradition as Chinese proverbs about time and work, and the habit of memorizing a rhyme is a large part of how farmers’ knowledge was passed down.
Another seasonal pattern is the nine-period counting that begins at the Winter Solstice, which people used to track the deepest cold.
Seasonal eating
The terms also guide what people eat, a custom closely related to regional cooking. Examples of widely reported habits, which differ by region and family, include:
- Around the Start of Spring, eating fresh spring vegetables, spring pancakes or spring rolls, in the spirit of welcoming the new season.
- At Clear Brightness, green rice dumplings in parts of the Jiangnan region.
- Around the Summer Solstice, cold noodles in some northern places, in keeping with the heat.
- At the Start of Fall, some families eat melon or other seasonal fruit.
- Around Frost Descent, persimmons in parts of the north.
- At the Winter Solstice, dumplings in the north and sweet rice balls in the south.
These are customs with many local variants, and not all are known to every family. In some of them, people relate food choices to traditional ideas about balance with the seasons, which are part of cultural history and not medical advice. Nothing here is a claim about health.
In art and daily life
The terms have appeared in poems, paintings and almanacs for centuries. Many classical poems are anchored to a specific term, such as the Clear Brightness poem by Du Mu, or poems about the frost and the first snow. Traditional almanacs printed the terms alongside lucky and unlucky days. In recent years, publishers and teachers have used the terms to introduce children to the old calendar, and social media and television programs mark each one with images and short explainers.
The terms today
For most urban residents, the terms are not directly useful for farming, but they still shape habits and conversation. People say that it is “time” for a certain food or a certain kind of weather, and the major terms are noted in the news. For a reader trying to understand Chinese culture, learning even a handful of them is a good way to see how the year looks from inside the tradition, with the sun marking the steps and festivals filling in between.