Popular Geography Science: Take you to know our home - Planet Earth 36. How much do you know about climate types - A mountain has four seasons
Tang Dynasty poet Bai Juyi has a poem: "The beauty of April in the world is gone, and the peach blossoms in the mountain temple begin to bloom." ("Peach Blossoms in Dalin Temple")
In April of the lunar calendar, spring has turned to summer at the foot of the mountain. Come, the peach blossoms growing on the top of Mount Lushan have just begun to bloom. In just a few words, the great poet revealed a universal natural law: the solar terms in the mountains come later than those in the mountains. This is because for every 100 meters of altitude increase, the temperature will drop by 0.6°C. The difference in temperature causes climate differences, which in turn affects the growth of natural vegetation. It is a typical phenomenon in which topographic factors affect climate, and is a natural geographical environment difference. One of the manifestations.
The differences in the natural geographical environment are mainly reflected in three aspects: longitude zone, dimensional zone and vertical zone.
If a person takes a train from Qinhuangdao in northern China to the northwest region during summer vacation, he will see the scenery outside the car window gradually transitioning from lush woods to endless grasslands, and finally It turned into a vast desert with a sea of sand. This change is mainly due to the fact that the farther west you go from the coast of eastern China, the closer you are to the interior of the continent, and the further you are from the ocean, making it difficult for moist airflow to reach, and the amount of precipitation is getting less and less. Although the latitude position and the amount of solar radiation received are similar, the water conditions are significantly different, forming different types of natural vegetation zones. This distribution pattern of natural zones that changes with longitude is called longitude zonality.
If a person travels north from Indonesia near the equator, across the Eurasian continent, and to the coast of the Arctic Ocean, he will see that the changing process of the natural vegetation belt is roughly: tropical rain forest belt - tropical monsoon forest belt - Subtropical evergreen broad-leaved forest zone - Temperate deciduous broad-leaved forest zone - Subarctic coniferous forest zone - Boreal tundra zone - Frigid ice sheet zone. The reason for such changes in the natural landscape is that from the equator to the poles, the amount of solar radiation received by the earth's surface gradually decreases, the temperature drops, and the overall rainfall also decreases, forming different climate types and vegetation types suitable for the climate. The pattern of changes in natural vegetation zones with latitude is called latitudinal zonality.
Vertical zonality is a change in temperature and precipitation caused by changes in altitude, and natural vegetation changes with altitude. The Lushan Mountain in Bai Juyi's poem is above 1,000 meters above sea level, and the climate at the top of the mountain is obviously different from that at the foot of the mountain. Compared with the climate in Jiujiang City, Jiangxi Province at the foot of the mountain, spring at the top of Lushan Mountain comes later, summer is shorter, autumn arrives earlier, and winter is longer. Lushan Mountain is located in a typical subtropical monsoon climate zone. The natural vegetation zone (base zone) at the foot of the mountain is a subtropical evergreen broad-leaved forest. As the altitude increases, the vegetation zone gradually transitions to a mixed evergreen and deciduous broad-leaved forest, and then to a temperate mountain deciduous broad-leaved forest. Forests, coniferous forests, shrubs, alpine meadows.
Similar to the changing pattern of the Lushan Mountain natural zone, there is the Hengduan Mountains in southwest China. The natural vegetation at the foot of the mountains is also a subtropical evergreen broad-leaved forest, but the Hengduan Mountains are at a higher altitude, with the main peak Gongga Mountain. The altitude exceeds 7,000 meters, and there is an ice and snow belt that does not melt all year round above the alpine meadow belt. Climbing from the hot foot of the mountain to the snowy top of the mountain, the changes in the natural landscape seen along the way are similar to trekking from Yunnan to the North Pole, and it seems like experiencing spring, summer, autumn and winter. In addition, the mountainous terrain is complex and the weather is changeable, so the locals use the term "Yishan". There are four seasons, and the weather is different for ten miles" to describe the climate in the mountains.
From the comparison between Lushan Mountain and Hengduan Mountain, it can be seen that the higher the mountain, the more complete types of vegetation zones it has. Assuming that there is a high enough mountain peak near the equator, the natural zone from the foot of the mountain to the top of the mountain is The changes would be similar to the changes in natural vegetation from the equator to the poles. In addition, the lower the geographical latitude of the mountain peaks, the more complex the natural spectrum is, and the higher the latitude, the simpler. For example, no matter how high the mountains in the Antarctic continent are, they will be completely covered with ice and snow, and no other vegetation belts can be found. In this case, the snow line height drops to 0 meters.
The snow line is the lower limit of the perennial snow area. The altitude of the snow line decreases with increasing latitude. For the same mountain peak, the height of the snow line is also different on the shady slope and the sunny slope, or on the windward slope and the leeward slope. Generally speaking, for mountain peaks in the northern hemisphere, the southern slope (sunny slope) has better sunlight, slightly higher temperatures, faster melting of ice and snow, and a higher snow line than the northern slope (shady slope). The windward slope of a mountain is rich in water vapor and receives heavy snowfall. The snow has no time to melt, and the height of the snow line is lower than that of the leeward slope. Slope aspect depends on the difference in temperature and precipitation to affect the position of the snow line. When the two conflict, the influence of precipitation is greater than the influence of temperature. For example, the southern slope of the Himalayas is both a sunny slope and a windward slope, and the actual snow line height is higher than that of the northern slope. Low. In addition, the height of the snow line is also affected by the local terrain. At the same altitude, if the slope in a place is very steep and the snow cannot be stored, it will easily slide to a lower position and melt, the height of the snow line will be higher than that of a slope with a gentler slope. high. The height of the snow line also changes seasonally, and is generally slightly higher in summer than in winter.
In addition to the above large-scale and large-space differences in the natural environment, there are also many smaller-scale differences. They are difficult to summarize into universally applicable rules, but they are everywhere, such as an artificial reservoir. The climate nearby is wetter and the vegetation is denser than areas away from the reservoir, and the temperature and humidity will be different between the front and back of a house. Just like "there are no two identical leaves in the world", differences are the main theme of nature.
Nature is much more complex than we imagine. Through long-term careful observation and research, scientists have summarized regular knowledge to facilitate people's learning. When we use knowledge, we cannot just copy it and need to combine it with local conditions. Only by revising knowledge based on actual conditions can we better understand the world we live in.