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24 Solar Terms - An introduction

Written by : CHOW Tak-Hing, LEE Tsz-cheung

The Chinese calendar's 24 Solar Terms, which are believed to originate from the Yellow River region, is a special calendar invented by the ancient Chinese based on knowledge in astronomy, climatology and agricultural meteorology. Solar Terms divide a year into 24 parts according to the Earth orbit around the Sun. Since the Earth takes about one year to complete its orbit once (360 degree), by dividing it into 24 equal segments, each 15 degrees (approximately 15 days) will mark a Solar Term. As such, the 24 Solar Terms generally represent the seasonal change over central China in a year and, in turn, closely relate to agricultural activities in ancient China.

Solar Terms are in general named according to the astronomical phenomena, climatological characteristics or agricultural activities prevalent at the respective times of the seasons. They are : "spring commences 立春", "spring showers 雨水", "insects waken 驚蟄", "vernal equinox 春分", "bright and clear 清明", "corn rain榖雨", "summer commences 立夏", "corn forms 小滿", "corn on ear 芒種", "summer solstice 夏至", "moderate heat 小暑", "great heat 大暑", "autumn commences立秋", "end of heat 處暑", "white dew 白露", "autumnal equinox 秋分", "cold dew 寒露", "frost 霜降", "winter commences 立冬", "light snow 小雪", "heavy snow大雪", "winter solstice 冬至", "moderate cold 小寒", and "severe cold 大寒".

To help memorize some of these terms, the Chinese has composed a "24 Solar Term Song" using the names of the Solar Terms.

春雨驚春清穀天
夏滿芒夏暑相連
秋處露秋寒霜降
冬雪雪冬小大寒

 

Located in southern China, Hong Kong's climate is very different from that of the Yellow River region. So the meaning of some of the Solar Terms, such as "light snow" and "heavy snow", are not applicable to Hong Kong. In the coming issues of the "Weather on Wings", we shall talk about the meaning of some interesting Solar Terms and the corresponding climatological statistics in Hong Kong. Please stay tuned.

<<Weather on Wings, May 2006>>

Last revision date: <01 Apr 2014>