section_path: Horology/Year/Solar year and solar terms
section_name: Solar year and solar terms
paragraph_text: Solar year and solar terms
  
  The solar year (traditional Chinese: 歲; simplified Chinese: 岁; pinyin: Suì), the time between winter solstices, is divided into 24 solar terms known as jié qì (節氣). Each term is a 15° portion of the ecliptic. These solar terms mark both Western and Chinese seasons, as well as equinoxes, solstices, and other Chinese events. Pairs of solar terms are referred to as climate terms. The first solar term in a pair is the "pre-climate" (節氣; 节气; Jiéqì), and the second is the "mid-climate" (中氣; 中气; Zhōngqì). The Zhōngqì are considered "major terms", while the Jiéqì are deemed "minor terms". The solar terms qīng míng (清明) on 5 April and dōng zhì (冬至) on 22 December are both celebrated events in China.
  
  The solar year (suì, 歲; 岁) begins on the December solstice and proceeds through the 24 solar terms. Since the speed of the Sun's apparent motion in the elliptical is variable, the time between major terms/mid-climates is not fixed. This variation in time between major terms results in different solar year lengths. There are generally 11 or 12 complete lunisolar months, plus two incomplete lunisolar months around the winter solstice, in a solar year. The complete lunisolar months are numbered from 0 to 10, and the incomplete lunisolar month is considered the 11th month. If there are 12 complete (and one incomplete) lunisolar months within a solar year, it is known as a leap year (a year possessing an intercalary month).
  
  Different versions of the traditional calendar might have different average solar year lengths. For example, one solar year of the 1st century BCE Tàichū calendar is 365 + 385 ⁄ 1539 (365.25016) days. A solar year of the 13th-century Shòushí calendar is 365 + 97 ⁄ 400 (365.2425) days, identical to the Gregorian calendar. The additional.00766 day from the Tàichū calendar leads to a one-day shift every 130.5 years.
  
  If there are 12 complete lunisolar months within a solar year, the first lunisolar month that does not contain any mid-climate is designated the leap, or intercalary, month. Leap months are numbered with rùn 閏, the character for "intercalary", plus the name of the month they follow. In 2017, the intercalary month after month six was called Rùn Liùyuè, or "intercalary sixth month" (閏 六月) and written as 6i or 6+. The next intercalary month (in 2020, after month four) will be called Rùn Sìyuè (閏 四月) and written 4i or 4+.