The Chunbun (Kor. 춘분, Chin. 春分, Spring Equinox), the fourth of the twenty-four solar terms, follows Gyeongchip (Kor. 경칩, Chin, 驚蟄, Day of Awakening from Hibernation) and precedes Cheongmyeong (Kor. 청명, Chin. 淸明, Day of Pure Brightness). It always occurs in the second lunar month and corresponds to the period around March twenty-first on the Gregorian calendar. On this day the sun, on its northbound path, crosses the celestial equator, i.e. the ecliptic meets with the equator. In the traditional worldview, such positioning of the sun vertically above the equator is interpreted as a dividing point between exactly equal amounts of positive energy yang (Kor. 양, Chin. 陽) situated due east and negative energy yin (Kor. 음, Chin. 陰) situated due west. Therefore, the name chunbun literally means “spring point of division.” As the influences of yin and yang are exactly equal on this day, the lengths of day and night are identical, as well as the number of warm and cold hours. Around this time of year, rural households plow barley fields, repair walls, and harvest wild greens.
During the Goryeo (918-1392) and Joseon (1392-1910) dynasties, the royal household held a worship service to Hyeonmyeongssi (Kor. 현명씨, Chin. 玄冥氏, the god of the North, associated with winter) on the spring equinox before taking out the ice from its ice chamber. In the Goryeo period, Chungbun was a day of rest for government officers. In the Gyeongju area, it was associated with the custom of visiting the tombs of the three kings Park (朴), Seok (昔) and Kim (金), who founded the Silla Kingdom (BCE 57 – CE 935) and the three main family clans.
The weather on the spring equinox was considered an important indicator of the harvest in the coming autumn and a predictor of any flood or drought which may lie ahead. According to the “Jeungbo Sasi Chanyo” (Kor. 증보사시찬요, Chin. 增補四時纂要, Revised and Augmented Abridged Account of Seasonal Customs), the 15th volume of the 18th century agricultural treatise the “Jeungbo Sallim Gyeongje” (Kor. 증보산림경제, Chin. 增補山林經濟, Revised and Augmented Forestry Economy), the occurrence of rain on the spring equinox was interpreted as a portent of a disease-free year. If bluish clouds were seen due north at sunrise, this was a harbinger for a great farming year for barley. In general, an overcast sky was a positive indicator, while a clear day without a cloud in sight was considered a bad omen because it predicted poor growth of vegetables, a weakness of livestock, and frequent heat-related illnesses. In addition, the colors of the clouds and direction of wind were also read and assigned meanings. Blue clouds predicted damage from insects; red clouds – drought; black – flood; and yellow – abundant crops. The wind from the east forecasted low prices and an abundant harvest of barley. The westerly wind was a sign that barley would be scarce in the year ahead. The southerly wind indicated a big amount of precipitation before the fifth lunar month and dry conditions afterwards, while the northerly wind meant that rice would be scarce that year.