Who knows why caves are warm in winter and cool in summer? total temperature
Tuyaodong in northern Shaanxi
Long, long ago, the wind brought the loess from the far north to the northwest plateau of China, day after day, year after year, thus forming the vast and thick yellow land of northern Shaanxi. Since there are people in this land, there are caves. These caves are places where the descendants of the Chinese people thrive and create splendid cultures.
Yan 'an, located in the middle reaches of the Yellow River and in the gully region of the Loess Plateau, is still the most important life form for people, whether in towns or villages. I have known caves since I was a child, but I didn't really know them until I went to Yan 'an recently and stayed in the most primitive earth cave for a few days.
Most human rooms are built according to local conditions, especially in the Loess Plateau. The bank of the earth cliff on the Loess Plateau is the natural terrain for digging caves. The earth cave is warm in winter and cool in summer, which is very suitable for living. As early as the Neolithic Age, clan tribes in the middle reaches of the Yellow River built simple caves and shallow caves with wooden frames and grass mud on the earth caves, and gradually formed settlements.
There are many kinds of caves in northern Shaanxi, including back mountain earth kiln, crevice earth kiln and flat stone kiln. In general, there are mostly brick kilns in cities, and most of them are earthen kilns or stone earthen kilns in rural areas. The most typical cave in northern Shaanxi is the backer kiln. They cut horizontal holes in the natural earth wall, often several holes are connected together, or several floors up and down. Some add brick coupons or stone coupons in the cave to prevent landslides, or build brick walls outside the cave to protect the cliff surface. Large-scale houses are built outside the cliff to form a courtyard, which becomes a cliff kiln.
When I came to Luozishan Township, Yanchang County, I met a family building a new cave. At first glance, a row of four-hole earth holes has basically taken shape. The cave is backed by loess and faces the highway, and two earth caves have been excavated on it. The soil dug out of the cave just covers the earth kiln below and becomes a flat roof. Several young people took part in building the kiln. They told me that the winter slack season is the best time to build caves, which is hard to meet at ordinary times. I'm glad to meet such a good opportunity to start a dialogue with the boys. They say there is great pressure to build new caves. The first thing is to find someone to see Feng Shui and choose the terrain. It is very important to choose the soil for digging caves. It must be clay. The cave should face the sun, the back of the mountain and the open area.
The newly-built caves are still in the traditional form. From the outside, the four holes should be separated. When you walk in, you will find that they have tunnel-like doors to communicate with each other and become a whole, connecting all members of the family. The cave is about 4 meters wide, 5 meters deep and 3 meters high, and the loess surfaces on both walls are very flat and smooth. The dome is semicircular. This makes the already spacious cave look very high and has a lot of space. From the inner wall of a cave kiln in the middle, there is a tunnel-like door leading to a completely dark cave with a warehouse for storing food and other items.
The kang and stove in this newly-built cave have been repaired, and some square concave holes have been dug in the wall to put things. The boys built brick windowsills and doors outside the cave. They said that when the last brick was placed in the middle of the arched door of the cave, it was all finished. After the completion, a grand celebration ceremony will be held. The host will stick red paper-cuts inside and outside the kiln, put couplets at the door and set off firecrackers. Relatives and friends in the village will come to congratulate them, and the host will invite them to drink and eat meat, which will be a lively event.
In front of several caves, I saw several women making zongzi. There were pots and stoves outside the door. I asked them if they were all cooking outdoors. One of the women in her thirties told me that most caves have two stoves, and only hot people can cook outdoors. She invited me into the house, and I walked into the cave with the dust and sweat of my journey, feeling cool. This cave is more than 20 square meters in size, and there is a big kang against the wall in the depth of the cave. Sister-in-law said it was called a kang. Some caves are called Qian Kang near the window. No matter whether it is the palm kang or the front kang, there is a three-hole stove at one end of the kang, which is a place for cooking at ordinary times. Because the flue of the stove fire passes through the bottom of the kang, it is very warm on the kang in winter. There is a concave hole in the wall above the stove, which contains oil, salt, sauce, vinegar and so on. On one side of the indoor wall stands a row of coarse porcelain pots of different heights, which are used to store water, food and pickles. In addition, there is a big red cabinet with patterns on it, clothes in it and some simple ornaments on it. There are all kinds of calendars and New Year pictures on the surrounding walls. In particular, the three walls around the Kang are about 1 m wide, and there are some papers with patterns and pictures pasted with various cigarette case papers, which they call Kang Wai, which is very beautiful.
Kang wai is a practical decoration, which can avoid the direct contact and friction between the bedding on the kang and the rough wall and keep it clean. In order to beautify the living room, many people draw circles on the kang. This is the folk art with a long history in northern Shaanxi-painting outside the kang.
The window of Yan 'an cave is perhaps the most exquisite and beautiful part of the whole cave. Arched holes are made of wooden lattices into various beautiful patterns. Windows are divided into four parts: skylight, inclined window, kang window and doors and windows. The loess plateau is criss-crossed with gullies and drab colors. In order to beautify life, the cave owner decorated the cave with paper cuts. According to the pattern of the window, they decorated the window grilles beautifully and appropriately. The window of the cave is the main light source of the cave. The window grilles are attached to the window, which are brightly colored from the outside and bright and comfortable from the inside, thus creating a unique formal beauty of light, color and tone.
In Xujiagou, Ansai County, I specially visited Wang Xian, a famous paper-cutting expert. Wang Xian is a rural woman of about 40 years old. If you look at her paper-cutting and painting, you can't help but admit that she is an excellent folk artist. On the arched roof of her cave, I saw a circular paper-cut with big characters written on it and some flowers around it. She said it was the flower at the top of the cave. She told me that there are many kinds of paper-cuts, such as window flowers, kang wall flowers, kiln top flowers, shrine paper-cuts, wedding and funeral paper-cuts, and different paper-cuts are posted at different times and occasions. She showed me different shapes, rich samples, beautiful and vivid paper-cuts, including the zodiac, dragons and phoenixes, flower baskets, butterflies and so on. I don't understand why such paper-cuts are rarely seen in other caves. She said with a smile, "If you come to northern Shaanxi around the Spring Festival, the windows of every household are covered with colorful window grilles. Especially for people who get married, window grilles are particularly rich and wonderful. The paper-cuts and window grilles in that house are simply a small exhibition. " I don't know how long it will take to make such a beautiful paper-cut. Wang Xianli took out a few pieces of red paper and an ordinary pair of scissors and began to cut them. In a short time, just like magic, eight identical lifelike paper phoenixes appeared in front of my eyes, which made you admire the ingenuity of working women on the yellow land. It is they and the strong men on the yellow land who created the rows of earth caves that are famous in China.