Junior high school geography

Temperate continental climate: mainly distributed in 40 ~ 60 Asia-Europe and inland areas of North America and southern South America. Because it is far away from the ocean, the humid climate is difficult to reach, so it is dry and rainy, and the climate is very continental. The annual and monthly temperature differences are the highest among all climate types. Moreover, the closer to the center of the mainland, the drier it is, the greater the annual and daily temperature difference, and the transition of vegetation from forest to grassland and desert.

It is located in the inland and the east coast of the mainland between 40 and 60-65 north latitude. Winter is controlled by continental climate, with the average temperature below 0℃ in Leng Yue in the south and close to -40℃ in the north. In the hottest month, the average temperature in the south is 26-27℃, and it is close to 20℃ in the north. The growing season is about 200 days in the south and only 50-70 days in the north. Belonging to this climate zone are: Northeast China, most parts of Siberia, most parts of Alaska and Canada, and the vicinity of the Great Lakes in the United States.

The generalized temperate continental climate includes temperate desert climate, temperate grassland climate and sub-frigid coniferous forest climate. The narrow concept will exclude the latter. It is very cold in winter, controlled by high pressure, and the lowest temperature reaches-73℃; In summer, the average temperature in July in the south reaches 26 ~ 27℃, and the highest temperature is 33℃, which is close to 20℃ in the north. The maximum annual change range is 62.3℃. Controlled by continental air masses throughout the year, precipitation increases from south to north (from west to east in North America), with annual precipitation below 200mm to about 400mm and 300-600 mm in the north. Natural vegetation from south to north, from temperate desert and temperate grassland, transits to subafrigid coniferous forest.

Mainly distributed in Eurasia and the inland areas of North America.

Controlled by the continental air mass all year round, it is dry and rainy. Winter is cold, summer is hot, and the climate changes greatly. yearly precipitation

The temperate monsoon climate appears on the east coast of Eurasia near 35 ~ 55 north latitude, including North China and Northeast China, most of Korea, northern Japan and parts of the Far East of the Soviet Union. In winter, affected by the northerly winds in high latitudes inland, polar continental air masses prevail, which are cold and dry; In summer, influenced by polar ocean air mass or denatured tropical ocean air mass, southeast wind and southeast wind prevail, with warm, hot and rainy seasons. The annual precipitation is about 1 000mm, of which about two thirds is concentrated in summer (hot and rainy in summer and cold and dry in winter). There are four distinct seasons throughout the year and the weather is changeable. With the increase of latitude, the temperature amplitude in winter and summer increases correspondingly, while the precipitation decreases gradually.

Tropical monsoon climate (tropical monsoon climate)

Distribution: it is distributed on the east coast of the mainland between north latitude10 ~ 25. Mainly distributed in Indo-China Peninsula and most parts of Indian Peninsula, and sporadically distributed in southern Taiwan Province Province, Leizhou Peninsula, Hainan Island and northern Philippine Islands; In addition, it is also distributed in the northern coastal zone of the Australian mainland.

Cause of formation: the difference of thermal properties between land and sea forms the winter monsoon, and the cold air mass from Mongolia and Siberia high turns right to the northeast monsoon due to geostrophic bias during the southward movement. The wind belt in the pressure area moves seasonally to form the summer monsoon, and the southeast trade wind in the southern hemisphere moves northward across the equator, and the southwest monsoon under the action of the geostrophic deflector is on the right.

Climatic characteristics:

1, the temperature is high all year round, the annual average temperature is above 20℃, and the most Leng Yue in winter is generally above 18℃ for half a year. The alpine plateau in the north blocked the invasion of cold air to the south, which made the temperature in this area relatively high for half a year in winter.

2. The annual precipitation is large, which is obvious in dry and wet seasons, and the precipitation is concentrated in summer. In summer, under the control of equatorial ocean air mass, there is more convective rainfall, and tropical cyclones bring a lot of precipitation, resulting in more rainfall in summer than in tropical dry and wet seasons. On some windward coasts, due to the influence of topography, the summer precipitation even exceeds that in the equatorial rainy climate zone. The annual precipitation is generally above 1, 0,500 ~ 2,000 mm. Winter is controlled by the dry northeast monsoon, and precipitation is scarce.

3. The northeast monsoon emitted by the land high pressure flows into the equatorial convergence zone on the ocean in the obvious dry season. In the rainy season, the southwest monsoon from the subtropical high in the southern hemisphere flows into the Tal low.

4. Tropical cyclones prevail. Synchronized with the "summer monsoon", tropical cyclones prevail from mid-May to mid-September every year.

Vegetation: tropical monsoon forest, savanna landscape in the transition zone to semi-arid climate.

The subtropical monsoon climate is distributed on the east coast of subtropical continent at 25 ~ 35 north latitude, and it is a zone where tropical marine air masses and polar continental air masses alternately control and compete with each other. It is mainly distributed in the south of Huaihe River in Qinling Mountains in eastern China, north of tropical monsoon climate, south of Japan and south of Korean Peninsula. It's not cold here in winter. The average temperature in 65438+ 10 is generally above 0℃, and it is hot in summer. The average temperature in July is generally around 25℃, and the direction of Xia Feng changes obviously in winter. The annual precipitation is generally above 1000 mm, mainly concentrated in summer and less in winter. This climate is most typical in the southeast of China. In other areas, because there is a considerable amount of precipitation in winter, there is little difference between winter and summer, so it is called subtropical monsoon humid climate.

This area is located between 25 and 35 north latitude and is divided according to the climate of planetary wind system. It is an arid area controlled by subtropical high. However, due to the difference between land and sea and the change of temperature and pressure field caused by the uplift of the Qinghai-Tibet Plateau, the monsoon circulation changed the circulation system of the near-surface planetary wind system, changed the arid continental climate into a humid subtropical monsoon climate, and changed the arid desert landscape into a humid evergreen broad-leaved forest landscape. After thousands of years of human activities, this area has become a densely populated and economically developed area in China.

The climate in this area is characterized by warm winter and hot summer, distinct four seasons, abundant rainfall and even seasonal distribution.

This area is rich in heat resources, with the annual average temperature 13℃ to 20℃ and the accumulated temperature ≥10℃ from 4000℃ to 6500℃. The monthly average temperature in 65438+ 10 is above 0℃, 0℃~2℃ in the north of the Yangtze River, 2℃~ 10℃ in the south of the Yangtze River and10℃ in Nanling area. Due to the low terrain and weak barrier function, Huaiyang Mountain is often affected by cold air from the south in winter, especially Jianghan Plain and Dongting Lake Plain, which are connected to Nanyang Basin in the north and Gui Xiang Corridor in Nantong. Winter becomes a channel for cold air to move southward, where the 65438+ 10 monthly isotherm protrudes southward in a tongue shape. The absolute minimum temperature in the north of the Yangtze River can reach below-10℃, and the minimum value of-18. 1℃ has appeared in Hankou (197765438+1October 30th), and it is mostly between -7℃ and-0 in the south of the Yangtze River. Whenever strong cold air goes south, the temperature often drops above 10℃. In Shanghai, there was a record that the temperature dropped by 25.2℃ in two days. Therefore, although this area is subtropical, the winter temperature is lower than other parts of the world at the same latitude. Due to the low temperature in winter, the subtropical latitude of China is south, and its northern boundary is 4~5 latitudes south of the theoretical boundary. Compared with the Mediterranean region, it is 10~ 1 1 latitude to the south. However, subtropical areas in China, especially central China, are generally hot in summer, with the average temperature in July around 28℃ and some areas exceeding 29℃. High temperature weather above 35℃ often occurs from May to September. July-August is controlled by subtropical high, with many sunny days and long sunshine hours. The frequency of high temperature is the highest, and the absolute high temperature often exceeds 40℃. Jinhua, Zhejiang and Anhua, Hunan have high temperatures above 465 and 438+0℃. The average temperature in April and1October is 16℃~2 1℃, and the temperature in autumn is slightly higher than that in spring.

Generally speaking, the middle and lower reaches of the Yangtze River are warm in winter and hot in summer, with four distinct seasons. Generally, winter is 1~4 months long, about 4 months north of the Yangtze River, and less than 1 month in Nanling area; Summer lasts for more than four months, generally ending from mid-late May to late September, and arriving at the beginning of 10 at the latest in the south. The length of spring and autumn in most areas is 2 months each, and it can reach 3 months in the south.

The average annual precipitation in this area is generally 800 mm~ 1600 mm, which is 1~2 times more than that in North China and richer than that in Southwest China. The distribution of precipitation decreases from southeast to northwest. The annual precipitation in hilly areas of Zhejiang Province is 1200mm ~ 180mm, that in Nanling mountain area and hilly areas of the south of the Yangtze River is about 1500 mm, and that in the middle and lower reaches of the Yangtze River is about1200mm. The influence of topography on precipitation is also remarkable. Generally, there are more mountains than flat land, and there are more windward slopes than leeward slopes. For example, Tunxi in Anhui is very close to Huangshan, and the precipitation in Huangshan is 700 mm more than that in Tunxi (Tunxi 1507.8 mm, Huangshan is 2263.9 mm). The annual precipitation of Luoxiao Mountain and Xuefeng Mountain can exceed 1800 mm.

In the seasonal distribution of precipitation, summer rain is the most, followed by spring rain, autumn rain is worse, and winter rain is the least, but winter rainfall can also account for more than 10% of the annual precipitation. The middle and lower reaches of the Yangtze River are areas with high proportion of winter rain and abundant spring rain in China.

This seasonal distribution of precipitation is closely related to the geographical location of the middle and lower reaches of the Yangtze River and the atmospheric circulation process.

The middle and lower reaches of the Yangtze River lie in the east of the Qinghai-Tibet Plateau. In winter, the north-south jet of the westerly belt meets over this area, forming a relatively stable shear line. Coupled with the influence of Nanling Mountains, a relatively durable quasi-static front in South China appeared on the ground, with frequent cyclones and extremely rainy weather. In most areas, the average precipitation in 65438+February and 65438+1October is about 40 mm~50 mm, and it is 60 mm in February. Since March, the warm and humid air flow in the south has strengthened and the precipitation frequency has increased. In late March, Gannan first entered the spring rain period, with this as the center, the spring rain gradually extended to the northwest, southwest and northeast (figure 12. 1.2). In most areas, the spring rain doesn't end until early and middle June. There is a lot of precipitation and a long rainy period in the hilly areas of the south of the Yangtze River. In most areas, the spring rain begins in early April and ends in late May, and the rainy season lasts for 60 days. There are more spring rains in this area, and the proportion of spring rains in Changsha and Nanchang is about 40%, which is more than summer rain. In Nanjing, Shanghai, Wenzhou and other places, spring rain accounts for about 25% of the annual precipitation.

tropical rainy climate

Also known as "equatorial rainy climate". Distributed between 5 ~ 10 on both sides of the equator. It is hot and rainy all year round, with an average monthly temperature of 25 ~ 28? Between c, the annual precipitation can reach more than 2000 mm. The seasons are evenly distributed, and there is no dry season. It mainly appears in Amazon Plain in South America, Congo Basin and Gulf of Guinea in Africa, most parts of Malay Archipelago in Asia and southern Malay Peninsula. They are mainly distributed in Amazon river basin in South America, Congo river basin in Africa, Gulf of Guinea, southwest coast of Indian Peninsula in Asia, Malay Peninsula, west coast of Indochina Peninsula, Philippine Islands and Irian Island, and Oceania extends from Sumatra Island to New Guinea.

Mainly because of latitude factors:

1. solar radiation: the amount of solar radiation is within the range of100-180 kcal/cm * year. It's hot all year round. Areas with stronger solar radiation will become deserts.

2. Atmospheric circulation: located in the equatorial low-pressure area, the trade winds gather and converge and rise near the equator, and the water vapor contained in it is easy to form clouds and cause rainfall.

3. Land and sea influence. Tropical rainforests are located at the seaside or in large river basins, which makes them abundant in rainfall and small in temperature difference. Low terrain, suitable for rainforest growth.

4. Vegetation has a great influence on the transpiration of trees, which makes the environment more humid.

The vegetation is a tropical rain forest.

mediterranean climate

Subtropical climate types. Named after the most typical Mediterranean coastal area.

Climate characteristics: hot and dry in summer, high temperature and little rain, mild and humid in winter.

The temperature is 5 ~ 10℃ in winter and 2 1 ~ 27℃ in summer. The annual precipitation is about 350 ~ 900 mm, which is concentrated in winter. Summer precipitation only accounts for 20 ~ 40% of the annual precipitation, and the maximum monthly precipitation is more than 3 times of the minimum monthly precipitation.

Reason: summer is controlled by subtropical high, the airflow sinks and there is little rain. In winter, the subtropical high moves to the low latitude, and the westerlies in this climate area have frequent cyclone activities and abundant precipitation. At the same time, the climate is mild and humid because the west wind blows from the warmer ocean in winter (the difference in thermal properties between land and ocean).

Distribution law: it is distributed on the west coast of the mainland between 30 and 40 north latitude.

Specific distribution area: There are five regions in the world with this climate:

(1) the Mediterranean coast, including southern Europe, the northern coast of Africa and a few areas in western Asia.

(2) the California coast of North America.

(3) the west coast of southern Africa, that is, western South Africa and southern Namibia (called the Cape of Good Hope region or the Cape of Good Hope region).

(4) Central Chile in South America.

(5) the southwest and southeast coasts of Australia (although it is southeast, it belongs to the west coast, near Adelaide, not Sydney).

It is also widely distributed, and it is the only climate type that exists in all continents except Antarctica.

Typical vegetation: subtropical evergreen broad-leaved forest. There are also dry shrubs or hard-leaved grasslands (Stipa, etc.). ).

Typical soil: cinnamon soil

mediterranean climate

1. Particularity of climate characteristics

The Mediterranean climate is characterized by westerlies in winter, frequent frontal cyclones, mild climate, the lowest monthly average temperature of 4 ~ 10℃ and abundant precipitation. Summer is controlled by subtropical high, the airflow sinks, the climate is hot and dry, the clouds are sparse, and the sunshine is sufficient. The annual precipitation is 300 ~ 1000mm, accounting for 60% ~ 70% in winter and only 30% ~ 40% in summer. The climate characteristics of rainy winter and dry summer are unique among various climate types in the world.

2. Typical climatic reasons

The Mediterranean climate is mainly caused by the westerlies in winter, with frequent frontal cyclones. In summer, controlled by the subtropical high pressure belt, the airflow sinks. Among more than ten climate types in the world, the climate types controlled alternately by pressure belts and wind belts throughout the year include tropical grassland climate (controlled alternately by equatorial low pressure belts and trade winds) and tropical desert climate (controlled alternately by trade winds and subtropical high pressure belts) in addition to the Mediterranean climate. The climate controlled by westerlies throughout the year is temperate maritime climate. From the analysis, it can be seen that the investigation of the causes of Mediterranean climate not only examines the students' mastery of the distribution of subtropical high (the maximum influence latitude is 20-40 degrees north and south latitude) and westerly belt (the maximum influence latitude is 30-60 degrees north and south latitude), but also examines the movement of pressure belt and wind belt. It can be said that if students can accurately understand the causes of the Mediterranean climate, it should be easy to understand other climates.

3. Widespread climate distribution

The Mediterranean climate distribution law is located on the west coast of the mainland between 30-40 degrees north and south latitude. Mediterranean climate is the only climate type that exists on all continents except Antarctica. Among the distribution areas of Mediterranean climate, the Mediterranean coast is the most obvious. Other areas such as California coast in North America, central Chile in South America, Cape of Good Hope at the southern tip of Africa and the southwest coast of Australia. Most of its distribution areas are economically developed and are also hot spots in the world.

tropical desert climate

Open classification: geography, region, tropics, deserts, climate

British weather in tropical desert

(1) The precipitation is small and the variability is large: Aswin in the Sahara Desert of North Africa has a record of no rain for many years; In Allica, a desert in northern Chile, South America, there have been only three showers that can measure rainfall in a row 17 years, and the total amount of the three showers is only 0.5 1 cm, so the precipitation is very small. Iquiji, also located in the desert of northern Chile, has no rain for four consecutive years, but in the fifth year, a shower dropped by 65,438+05 cm, and in the second year, a shower record reached 63.5cm, showing great variability. Rainfall in tropical deserts is mostly explosive showers, which often cause serious soil erosion.

(2) High temperature and large temperature difference: Due to less clouds, strong sunshine, insufficient vegetation coverage and low air humidity, the temperature rises extremely rapidly during the day. It is recorded that the temperature in North Africa is as high as 58℃. Generally, the average monthly temperature in summer is between 30℃ and 35℃, and the high temperature lasts for a long time. For example, in Aden, Arabian Peninsula, the monthly average temperature is above 30℃ for five months in a year. The desert is cooler at night, because there is no cloud all night, and the ground radiation is strong and the heat dissipation is fast. The lowest temperature at night is usually between 7℃ and 12℃, and there are also days of thin frost. The annual temperature difference is generally around 10℃~20℃, and the daily temperature difference is even larger, between 15℃~30℃. At a weather station south of Tripoli in North Africa, 1978,1February 25th, 978, it was recorded that the highest temperature in Jedaias during the day was 37.2℃, but at night, the lowest temperature dropped to -0.6℃, and the daily temperature difference reached 37.8℃, which was really "wearing a fur coat in the morning and wearing yarn in the afternoon".

(3) Strong evaporation and low relative humidity: Tropical desert climate is often cloudless, windy, sunny, high temperature and low relative humidity in Wan Li, so it has strong evaporation. The possible evapotranspiration is 20 times or even about 100 times of precipitation. The relative humidity in the air is very small, and it often appears at about 2% in the Sahara desert of Egypt.

The tropical desert climate is mainly distributed in the inland areas where the Tropic of Cancer passes and the west coast of the mainland, with the Sahara desert in northern Africa being the most extensive. First of all, we should have a general understanding of the characteristics of tropical desert climate:

Below, we will introduce the representative of tropical desert climate in detail.

Sahara in the Sahara Desert of Africa

The gateway to the Sahara desert

The Sahara desert is the largest desert in the world. Located in northern Africa, it stretches from the Atlantic Ocean in the west to the Nile River in the east, from the foothills of Atlas in the north to Sudan in the south, covering an area of more than 700 square kilometers. Atlas Mountain separates the Sahara desert and turns into an Anglo-green and clear Mediterranean landscape to the north. Algerian argyle, Moroccan Casa Blanga and other tourist areas are concentrated here.

Since ancient times, Sahara, a lonely nature, has refused people to live in it. The wind-blown sand movement dominates this spectacular world, and wind erosion and sand accumulation have caused this extremely dry surface. In this vast area, the appearance of oasis is often the most desirable paradise for desert travelers. With the different natural ecology of desert, desert residents are engaged in all kinds of farming or miscellaneous grain planting, and even nomadic people who live on aquatic plants. The hard life of the desert people adds a bit of excitement to this lifeless desert.

Murals in the Sahara Desert

Sahara desert is the largest desert in the world, with a hot and dry climate. However, what puzzles modern people is that there was a prosperous ancient civilization in this extremely arid and water-deficient mining area with cracked land and few plants. Many exquisite large-scale murals in the desert are the crystallization of this ancient civilization.

People are not only puzzled by the drawing date of these murals, but also ignorant of the strange shapes in them, which has become a mystery in the history of human civilization.

/kloc-in 0/850, the German explorer barrs came to the Sahara desert for investigation, and accidentally found ostriches, buffaloes and various figures carved on the rock wall. 1933, French cavalry came to the Sahara desert, and unexpectedly found several kilometers of murals on Tahiti Island and N 'asir Plateau in the middle of the desert. They are all painted on the rock shadow formed by water erosion, colorful, elegant and harmonious, depicting the life scenes of ancient people.

There are many animal images in the mural group, with various types and characteristics. The tense scene of animals flying in the air after being frightened is vivid and superb in creative skills, which can be compared with the excellent mural works of any country in the same era. From these animal images, we can infer the natural characteristics of ancient Sahara quite reliably. For example, some murals have canoes to hunt hippos, which shows that there used to be rivers flowing in the Sahara.

From this point of view, perhaps the desert is the birthplace of human ancestors!

desertification

The so-called desertification refers to creatures on land. The decline or even loss of its productivity is mainly due to the destruction of the natural environment by human beings. One of the most obvious places of desertification is in Sachl, south of the Sahara Desert. In the northern part of this area, sheep and camels are raised by nomadic or grazing methods, which eats up all the plants in the whole area and creates a bare land. However, in the humid and wide south, due to the over-reproduction of livestock and the lack of cultivated land, the whole area has gradually become barren.

Coupled with the shortage of water, people began to dig wells. When people gather together to look for water, there are more livestock, which accelerates the deterioration of the environment and encourages desertification. This vicious circle makes people's lives in this area generally very difficult. There is no rainy season in the Sahara desert, so it won't rain, but as long as there is a little moisture, plants sleeping underground will compete to sprout new buds, but soon, overgrazing livestock will eat them up ... So the desertified soil is still expanding silently ...

I hope our motherland will not be swallowed up by the desert ... of course, it depends on the efforts of our generation!

What is a mirage? How is it formed?

In the desert, the lost people were short of water and food, and suddenly they saw the oasis, but when they got closer, they found that it was just a mirage. They were so happy. Although this is a common bridge in movies, it is a mirage, and nature is playing with us with the magic of light. It is caused by refraction and total internal reflection of light in air.

Mysterious places always have magical scenery, don't they?

Desert ship

Under the scorching sun and through the rolling sandstorm, camels shuttle back and forth in the desert, carrying people and goods through the driest areas. Their body functions are very adapted to the desert environment and they can go without drinking water for several days. In order to retain water, the camel's body temperature will rise a lot before it starts to sweat, so as to reduce the amount of sweating. In addition, their excrement is highly concentrated urine and dry feces. Camels feed on rough and tough desert plants and can survive for a long time by relying on the fat stored in the hump. Camels can be divided into two types: single-humped camels and double-humped camels. African camel metal dromedary has been domesticated and raised by people.

This can be compared with China's workhorse, right?