Alpine cold

Alpine cold

Geographical term, a kind of climatic characteristics. It refers to the extremely cold climate area caused by high altitude or high latitude.

overview

High cold in geographical sense refers to a kind of climatic characteristics of the climate. It is generally used to describe the extremely cold climate area caused by high altitude or high latitude. The high altitude and cold climate is because human beings mainly live in the troposphere of the earth's surface layer. In this circle, the temperature changes have a certain relationship with the altitude, that is, the temperature will drop by about 0.6 ℃ every 100 meters above sea level. According to this principle, the higher the altitude, the colder the climate. This is the meaning of the so-called "too high to be cold". For example, one of the most significant physical and geographical features of the Tibetan Plateau in China is the high cold. In addition, because of the high latitude and cold areas, roughly follow the fact: because the earth is a non luminous tilt irregular sphere, the sun light from a distant place, will lead to uneven light and heat on the whole earth surface, equatorial solar altitude angle is large, solar radiation is strong, and the more light and heat, and the more toward the north and south poles, the higher the solar altitude angle The smaller the temperature is, the less light and heat will be obtained. As a result, the climate will become quite cold in high latitudes. For example, the Antarctic continental region (floating population), the Arctic coastal region. Whether it is high altitude or high latitude, the cold climate creates a special geographical environment. This has an important impact on human survival activities.

Alpine town

The village of oimyakon basin in Russia - oimyakon town. One of the "cold poles" in the northern hemisphere. It is located in the upper reaches of the indigirka River in northeast Siberia. From December to January of the next year, the day and night average temperature is lower than - 45 ℃, and even below - 60 ℃ in some years. The absolute minimum temperature was - 71 ℃, and the absolute annual temperature range was 101.8 ℃. It is one of the regions with the largest annual temperature range in the world. This is considered to be the coldest human settlement on earth. The lowest temperature here once reached minus 71 degrees Celsius. It is said that many people were forced to amputate their limbs because of severe frostbite at that time, resulting in the shortage of narcotic drugs in local hospitals.

This beautiful valley fully demonstrates the extreme cold of Siberia under the control of high pressure. The cold wind will not blow down the snowflakes on the trees, the sky is high and blue, crystal clear, and the thin white fog is around. Local people's wooden houses are built on this permafrost, and the heat inside the houses gradually softens the frozen soil, so the houses on the whole street look like tottering. In order to survive in this extremely cold environment, it is necessary to ingest a lot of fat and protein to maintain the body functioning. The most common food for local people is roast horse meat and frozen raw horse liver. They eat meat three times a day and at night. In a few days, you will feel as if there is a strong horse in your body. There is a special natural phenomenon in this area. The higher the altitude, the higher the temperature. This does not seem to conform to a basic rule of atmospheric physics. Even experienced meteorologists are difficult to make an accurate explanation.

In this extremely cold place, hunting becomes very simple. You just need to set traps in places where mammals come and go. There is no need to crouch and watch at all. The temperature here is much lower than that in the freezer of the household refrigerator. The trapped animals are like being put into the cold storage, and will not thaw for several months. The natural preservation effect is very ideal. In addition, many unusual things will happen in the cold life: fishing under the ice, deer pulling sleds, defrosting horses If you want to experience it, you must be prepared. Any clothes you usually wear can't survive the winter there.

roof of the world

The Qinghai Tibet Plateau, with an average altitude of more than 4000 meters, stands in the middle of the troposphere. Compared with the free atmosphere at the same altitude, it has the warmest climate, the highest humidity and the lowest wind speed. But on the ground, compared with the surrounding areas at the same latitude, the climate here is coldest, driest and the wind speed is the highest. This is the result of the dynamic and thermal effects of the huge plateau.

The general characteristics of plateau climate are: strong radiation, more sunshine, low temperature, less accumulated temperature, and the temperature decreases with the increase of altitude and latitude. It is estimated that the annual average temperature will decrease by 0.57 ℃ when the altitude increases by 100 meters and 0.63 ℃ when the latitude increases by 1 degree. The diurnal range is large; the humidity is distinct and rainy at night; the winter is cold and dry with strong wind; the summer is cool and rainy with hail; the four seasons are unknown. The average temperature in January and July is 15-20 ℃ lower than that in the eastern plain of the same latitude. According to climate classification, there is no summer in Tibet all year round except for the valley area in the southeast margin. The annual total radiation is 5850-7950 MJ / m2, which is 0.5-1 times higher than the eastern plain at the same latitude.

The annual average temperature of the Qinghai Tibet Plateau is low, which constitutes the main characteristics of the climate. Hoh Xil, located in the northern Tibetan Plateau, has an annual average temperature below 4.1 ℃. The isotherms coincide with the contours, forming a closed low temperature center. It is the lowest temperature area in the Tibetan Plateau and the lowest temperature area in the same latitude of the northern hemisphere. There is less precipitation and great regional difference. The annual precipitation of the plateau gradually decreases from more than 4000 mm in Southeast Tibet to the cold lake in Qaidam Basin, and the precipitation of the cold lake is only 17.5 mm. Taking bashika in the Yarlung Zangbo River Valley as an example, the precipitation is extremely abundant, with an average annual precipitation of 4500mm, which is 200 times of the minimum precipitation.

Hypobaric hypoxia

Atmospheric pressure changes with altitude, and the partial pressure of various gases that make up the atmosphere also changes with altitude, that is, it decreases with altitude. So is the partial pressure of oxygen. The atmospheric pressure decreases in plateau area. The oxygen content and oxygen partial pressure in the atmosphere decrease, so does the oxygen partial pressure in human alveoli. The oxygen diffused into the blood of pulmonary capillaries will decrease, and the arterial oxygen partial pressure and saturation will also decrease. When the oxygen saturation decreases to a certain extent, the oxygen supply to various organs and tissues will be insufficient, resulting in functional or organic changes, and then the symptoms of hypoxia, such as headache, dizziness, dizziness, etc Memory loss, palpitation, shortness of breath, cyanosis, nausea, vomiting, loss of appetite, abdominal distension, fatigue, insomnia, blood pressure change, etc. This is also the root cause of all kinds of high altitude diseases.

Cold and dry

The temperature gradually decreases with the increase of altitude. Generally, the temperature decreases about 6 ℃ for every 1000 meters. In most areas of the plateau, the air is thin, dry and cloudless. During the day, the ground receives a lot of solar radiation energy, and the temperature near the surface layer rises rapidly. At night, the ground dissipates heat very fast, and the surface temperature drops sharply. There is a big difference between the maximum temperature and the minimum temperature in a day on the plateau. Sometimes, the temperature is as high as 20 ~ 30 ℃ in the daytime, and sometimes it can drop below 0 ℃ in the evening and early morning. This is also a major feature of the plateau climate. Due to the low atmospheric pressure and water vapor pressure on the plateau, the water content in the air decreases with the increase of altitude, so the higher the altitude, the drier the climate. When the wind speed is high on the plateau, the water loss on the body surface is significantly higher than that on the plain, especially when working or strenuous activities. At the same time, due to the influence of diuretic factors such as high altitude hypoxia and cold, the water content of the body is reduced, resulting in abnormal dryness of respiratory tract mucosa and whole body skin, reduced defense ability, and prone to pharyngitis, dry cough, epistaxis and chapped hands and feet.

Long sunshine and strong radiation

The air in plateau is thin and clean with less dust and water vapor. The atmospheric transparency is higher than that in plain areas. The solar radiation transmittance increases with the increase of altitude. The main influence of strong ultraviolet and solar radiation is that the exposed skin and eyes are prone to damage. The skin damage is characterized by sunburn, edema, pigmentation, skin thickening and wrinkles. The strong ultraviolet radiation in the sunlight of plateau area is easy to cause acute eye injury, mainly causing acute keratitis, cataract, visual impairment and snow blindness. Other factors such as high altitude hypoxia often lead to gastrointestinal peristalsis, saliva, intestinal juice and bile secretion decreased, loss of appetite, indigestion and malabsorption.

Chinese PinYin : Gao Han