China's '24 solar terms' was added to the United Nations Educational, Scientific and Cultural Organization’s (UNESCO) world intangible cultural heritage list.It is a knowledge system and social practice formed through observations of the sun's annual motion, and cognition of the year's changes in season, climate and phenology.It is known as "the fifth great inventions of China."

The dark area formed by light exposure to an opaque object is called shadow.Ancient Chinese divide the time of the sun movement trajectory into 24 equal parts by shadow,each part was a slar term.

As early as the Shang Dynasty(17th century BC - 1046 BC),the ancient Chinese had already estabished 4 major slar terms by observing the length of the shadow . The day of the longest shadow was called the Winter Solstice,and the day of the shortest shadown was called the Summer Solstice.The days of the precise middle was called the Spring Equinox and the Autumnal Equinox.This four solar terms was used to indicate the length of the day and the night.

the Winter Solstice:In a year,the the Winter Solstice is the day shortest daytime and longest nighttime in the north hemisphere.And then,the daytime will get longer every day.

the Vernal equinox :The time of day and night is equal all around the world.The daytime is beginning longer than the nighttime in the north hemisphere.

the Summer Solstice:In a year,the the Winter Solstice is the day longest daytime and shortest nighttime in the north hemisphere.And then,the daytime will get shorter every day.

the Autumnal Equinox:The time of day and night is equal all around the world.The daytime is beginning shorter than the nighttime in the north hemisphere.

During the Zhou Dynasty(1046 - 256 BC),the other four slar terms had been developed.They were used to indicate the beginning of the four season of the year.

the Beginning of Spring:All things recovery,full of vigour.

the Beginning of Summer: All things grow exuberant.

the Beginning of Autumn:The sky is clear and the air is crisp and the moon is bright.

the Beginning of Winter:The weather is turning cool and crops enter the overwintering period.

After then,the ancient Chinese summed up 16 other slar terms in continuous farming and labor.Add the previous 8 slar terms,that's the 24 slar terms we're using now.In 104 B.C.,Deng Ping formally booked the 24 solar terms in the calendar, defining the astronomical position of the 24 solar terms.

5 solar terms used to indicate the change in temperature.

Lesser Heat:The temperature gradually increased, into the summer drought period.

Greater Heat:Extremely hot.

the End of Heat:The temperature began to decline.

Lesser Cold:The temperature is approaching the lowest.

Greater Cold:The temperature is the lowest.

7 solar terms used to reflect the weather phenomenon.

Rain Water:The ice and snow began to melt and the rainfall increases.

Grain Rain:The rainfall increase significanty and cold wave weather basically over.

White Dew:The rainfall decrease significanty and dew began to appear on the plant.

Cold Dew:The dew became cooler and about to frost.

Frost's Descent:Condensation of dew to frost.

Lesser Snow:It begins to snow, and the snow is usually small.

Greater Snow:It begins to snow hard.

2 solar terms used to reflect the phenological phenomena.

the Waking of Insects:The spring thunder is coming,the hibernating animals began to wake up.

Pure Brightness:The air is fresh and the scenery is bright.

2 solar terms used to prompt agricultural cultivation.

Lesser Fullness of Grain:The crop matures in the summer began to fill up, but unripe.

Grain in Beard:The busiest time of the year for the farmers.

Although the 24 solar terms was invented about 3000 years ago,it's still suitable for us to use today.In the long river of human history, the ancestors of the Chinese nation have created a splendid culture with labor and wisdom.

中国的二十四节气被联合国教科文组织列为世界级非物质文化遗产。“二十四节气”是中国人通过观察太阳周年运动，认知一年中时令、气候、物候等方面变化规律所形成的知识体系和社会实践，被誉为“中国的第五大发明”。

光照射不透明物体而形成的较暗区域被称为影子。数千年前的中国人正是通过观察影子把地球围绕太阳周年运动轨迹划分为24等份，每一份便是一个节气。

早在殷商时期（约公元前1600年），古人通过观察正午太阳光照射在一根竖在平面上杆子所形成影子的长短，划分出了最初始的四个节气：影子最长的一天叫做冬至，最短的一天叫做夏至，影子长度居中的叫做春分和秋分。这四个节气用来表示白天和黑夜的长短。

冬至：北半球一年中白天最短，黑夜最长的一天。北半球从冬至开始白天越来越长。

春分：全球各地昼夜等长。春分过后，北半球白天开始比黑夜长。

夏至：北半球一年中白天最长，黑夜最短的一日。北半球从夏至开始白天越来越短。

秋分：全球各地昼夜等长。秋分过后，北半球开始白天比黑夜短。

到了周朝（约公元前1000年），又发展出了立夏、立春、立秋、立冬四个节气，用来表示一年中四个季节的开始。

立春：开始进入进入春天，万物复苏，生机勃勃。

立夏：夏季的开始，从此进入夏天，万物生长旺盛。

立秋：秋天的开始，秋高气爽，月明风清。

立冬：冬季的开始，天气开始转凉，农林作物进入越冬期。

再后来，古人在不断的农耕劳作中又总结出了另外的十六个节气名称，加上之前的8个节气，也就是我们现在使用的二十四节气。公元前104年，由邓平等人制定的《太初历》，正式把二十四节气订于历法，明确了二十四节气的天文位置。

用来表示气温变化的5个节气。

小暑：气温升高，进入伏旱期。

大暑：高温酷热。

处暑：气温开始下降。

小寒：气温接近最低。

大寒：气温达到最低。

用来表示反映天气现象的7个节气。

雨水：气温回升、冰雪融化、降水增多。

谷雨：降雨明显增多，寒潮天气基本结束。

白露：降水明显减少，植物开始有露水。

寒露：气温下降，地面的露水更冷，即将凝结成霜。

霜降：露水凝结成霜。

小雪：开始降雪，一般雪量不大。

大雪：雪量开始加大。用来表示物候现象的2个节气。

惊蛰：春雷始鸣，冬眠的动物开始醒来。

清明：气清景明，万物皆显。

用来表示农事要求的2个节气。

小满：夏熟作物的籽粒开始灌浆饱满，但还未成熟。

芒种：夏熟作物要收获，夏播作物要下地，是一年中最忙的季节。

时至今日，我们依然可以从中汲取智慧和精神力量。在人类历史的长河中，中华民族的祖先用劳动和智慧创造了光辉灿烂的文化。中国的传统文化是中华民族人文精神的积淀，是我们的民族之根、民族之魂。

Chinese Traditional Culture (1.Wedding Customs)

I will introduce Chinese traditional culture (3.Traditional Chinese Festivals) next time，see you~

Walking in the park around