What's the climate like on the west coast of France? Temperature change ()

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First, the basic characteristics of climate

The climate in Europe is characterized by its remarkable maritime nature. Although Europe is located in the middle and high latitudes, it is not as cold in winter as in northern Asia. Siberia is cold at -30-40℃, and most parts of Europe at the same latitude are above-15℃, even around 0℃, and it is not very hot in summer. The seasonal distribution of precipitation in Europe is relatively uniform, and there is no distinction between dry and wet seasons in most areas.

In addition, the temperate maritime climate in western Europe and the Mediterranean climate in southern Europe not only have distinct characteristics, but also cover a wide range.

Second, the main factors that form the climate in Europe

Geographical factor

The above characteristics of European climate are produced under the comprehensive influence of many factors, among which geographical location plays the most important role.

The continental part of Europe lies between 36-7 1 N, and the surrounding islands are roughly between 35-80 N. Most of the whole continent is located in the north temperate zone, so the temperate climate is dominant, the cold climate is limited and there is no tropical climate.

The latitude of Europe belongs to the westerlies in the planetary wind system. At the same time, Europe is located on the west coast of the mainland, facing the Atlantic Ocean and backed by the hinterland of Asia and Europe. Therefore, the air in the Atlantic Ocean can go deep inland with the westerly wind, which makes all parts of the continent affected by the ocean to varying degrees, which lays the foundation for the oceanography of European climate.

The North Atlantic Warm Current has a great influence on the climate in Europe. Originally a continuation of the Gulf of Mexico warm current, it flows from the east coast of North America to the northeast coast of Europe, becoming an important heat source in Europe, which has a very significant impact on the winter climate in Europe, making the winter temperature in Western Europe much higher than the average temperature at the same latitude, and also making the southwest Barents Sea in the Arctic Circle freeze all year round.

The slightly triangular horizontal profile based on southern Europe reduces the influence range of the cold Arctic Ocean. Going deep into the oceans and bays inside the mainland not only regulates the temperature in coastal areas, but also helps cyclones go deep into the land and deepen the oceanography of European climate.

The mountains in Europe are generally not very high, and most of them are close to the latitude direction, which does not stop the airflow from running from west to east. The great plains are more conducive to air mass movement. Therefore, Europe has become the smallest arid and semi-arid region in the world, which also determines that the climate type in Europe is relatively simple.

In a word, the geographical position of Europe creates the prerequisite of European maritime climate, and ocean currents, horizontal contours and landforms play a role in promoting and deepening European maritime climate, making Europe the most widely distributed and typical maritime climate in all continents of the world.

Circulation factor

There are four atmospheric pressure systems that have the greatest influence on the weather and climate in Europe: azores high and Iceland depression in the Atlantic Ocean, Mongolian high in Asia and South Asia depression. With the change of seasons, their strength rises and falls, and each plays a different role.

In winter, azores high retreated in the North Atlantic, only affecting the southwest corner of Europe, while Mongolian high-pressure forces extended westward to the southeast of Europe, forming a high-pressure axis across the Eurasian continent with azores high. Generally speaking, this high pressure axis is the boundary of European winter airflow (Figure 9). Under the strong influence of Iceland low pressure, the isobar on the north side of the high pressure axis extends to the southwest-northeast direction, and the pressure gradient is large, and the west wind or southwest wind prevails; In the south of the high pressure axis, the wind direction is more complicated due to the existence of the Mediterranean low pressure lake, which is roughly in the west of the Balkan Peninsula, dominated by westerly winds and northwest winds, and dominated by easterly winds and northeast winds in the east.

The air pressure in summer is quite different from that in winter (Figure 10). At this time, the Mongolian high has completely disappeared, and Asia is shrouded in the South Asian low pressure system, while azores high has been strengthened and developed, and its high pressure tongue extends to southern Europe, making southern Europe under the control of stable anticyclone weather; Iceland's low pressure is far less powerful in summer than in winter, but most parts of Europe are still affected by it. However, the westerly airflow at this time is not as stable as in winter, and it only performs well in the south of 60 north latitude, and the westerly wind or northwest wind is often blown. The influence of northern Europe and northern Europe has been strengthened. Although the westerly circulation is still the basic form of atmospheric circulation in Europe, its influence is far less than that in winter. The distribution of summer temperature in Europe is mainly determined by radiation factors, and the isotherm extends to near latitude line. In July, the 20℃ isotherm passed through the northern Iberian Peninsula, southern France, the southern foothills of the Alps and the northern Hungarian plain, and reached the southern Urals eastward. The western part of the isotherm is slightly south, indicating the influence of the ocean on the continental temperature distribution, and the eastern part is obviously north, indicating that the continental climate here is significantly enhanced. The average temperature along the Arctic Ocean in July is around 10℃, which is the lowest temperature in summer in Europe. The summer temperature in southern Europe and the Mediterranean is the highest, generally around 25℃, and in some places it can reach 28-29℃.

In short, it can be seen from the isotherm diagram that there is no high-temperature area with a monthly average temperature higher than 30℃ in Europe, and there are few cold areas with a monthly average temperature lower than -20℃. In winter, the temperature generally decreases from west to east or from southwest to northeast, and gradually increases from north to south in summer. The annual variation of temperature gradually increases from west to east, indicating that the eastern part is becoming more and more continental and less maritime. However, even in the Urals, it shows the influence of the Atlantic Ocean on the climate. Due to the influence of polar high, northerly winds often blow in most areas.

The distribution and seasonal variation of air pressure in Europe and its surrounding areas determine the nature of the air mass running over Europe and its influence on the weather and climate in Europe.

The air mass moving over Europe can be divided into three types: polar air mass, glacial air mass and tropical air mass, and each type can be divided into marine air mass or continental air mass according to its origin.

The ice front formed by the intersection of ice air mass and polar air mass (mainly polar air mass) is most obvious in winter, which has a great influence on the weather and climate in northern Europe. The polar air mass and tropical air mass form a polar front, and the polar front in Europe is divided into two branches: the northern branch is mainly formed by polar ocean air mass and tropical ocean air mass, which is located on the ocean surface near the British Isles, with a south position in winter and a north position in summer; The southern branch is formed over the Mediterranean Sea, and it is called the Mediterranean Front, which is mainly the interface between the polar continental air mass and the tropical continental air mass. Because southern Europe is controlled by subtropical high in summer, the Mediterranean front only appears in winter and disappears in summer.

Air mass movement is usually related to frontal and cyclone activities. Cyclone activity in Europe is the most prosperous in winter, covering the whole of Europe from Iceland in the north to the Mediterranean in the south. Among them, the polar front cyclone in the north has the most far-reaching influence on Europe, and it plays a prominent role in the heat and water exchange between the Atlantic Ocean and the European continent. In summer, due to the weakening of Iceland's low pressure, the pressure gradient decreases and the frequency of cyclone activity decreases.

Thirdly, the distribution characteristics of temperature and precipitation.

(1) temperature

From the isotherms of 65438+ 10 and July, it can be seen that the temperature distribution in winter and summer in Europe is very different. As far as the whole continent is concerned, in winter, circulation factors dominate; In summer, radiation plays a leading role.

1. Winter temperature distribution characteristics In winter, due to Iceland's strong and low pressure and frequent cyclone activities, large-scale heat exchange takes place between the Atlantic Ocean and the European continent, and the climate in most parts of Europe is mild. According to research, the North Atlantic Warm Current, known as the European heat source, brings heat to the British Isles and Scandinavia every year, which is equivalent to one-third to one-half of the total solar radiation obtained by these areas every year. So although the latitudes in these areas are quite high, the temperature in winter is not low.

The European 1℃ isotherm generally goes south along the west coast of Scandinavia to the western end of Alps, and passes through the Po River Plain, the western and southern Balkans to the south bank of Clim Peninsula. This isotherm divides Europe into two parts: cold and warm. Western and southern Europe are generally mild in winter, with temperatures above 0℃. 65438+ 10 +5℃ isotherm passes through the western British Isles and the west coast of France. Evergreen plants can grow west of this line. The average temperature of 65438+ 10 in most parts of southern Europe is above +5℃, and it can reach 12- 13℃ in some places, and the temperature is lower only in the central and northern Balkans. In northern Europe, eastern Europe and eastern Central Europe, the role of polar continental air masses is enhanced, ice air masses often invade, and winter is cold. 5438+ 10, the average temperature in northern Urals in June dropped to about -20℃, which is the lowest monthly temperature in Europe. Although serious, it is still "moderate" compared with Asia.

The winter temperature in most parts of Europe is positive anomaly, which is higher than the average temperature at the same latitude. Generally, the positive anomaly number in the northern region is higher than that in the southern region, and the annual average temperature in the western part of Scandinavia/kloc-0 is more than 20℃ higher than that in the same latitude, which is unique in all continents in the world.

2. Characteristics of temperature distribution in summer. In summer, due to the weakening of Iceland's low pressure, azores high enveloped southern Europe, and the polar high pressure had little effect on Europe.

(2) Precipitation

1. Distribution law of precipitation area in the western half of Europe, except the northern part of northern Europe and the southeastern part of Iberian Peninsula in southern Europe, there is generally more precipitation. This area with more precipitation extends to eastern Europe in a wedge shape and reaches the south-central part of Ural Mountains (Figure 13).

The distribution trend of precipitation in Europe clearly reflects the role of circulation factors. The Atlantic air mass rich in water vapor, especially the tropical Atlantic air mass, brings a lot of water vapor to the land as the cyclone moves from west to east. The more precipitation in the west, the weaker the cyclone intensity and frequency, and the less precipitation in the east. The role of Nordic glacier front is more and more important. Due to the low water vapor content in the atmosphere, there is generally little precipitation. Affected by the Eurasian high axis, the southern part of Eastern Europe has a small cyclone frequency and less precipitation. The low rainfall area in Iberia is related to the local high pressure.

It can be seen that the regional distribution of precipitation in Europe, on the one hand, shows a change from west to east, and at the same time there are zonal differences in latitude. The influence of topography makes this rule more complicated. The precipitation in mountainous areas is always more than that in adjacent plains, and the precipitation on windward slopes is always more than that on leeward slopes. Southern Iceland, western Scandinavia, the British Isles and Iberian Peninsula, the outer side of Alps, the west side of Apennines and the Alps in Dunac are the areas with more precipitation in Europe, generally above 1 000 mm, and some places even record annual precipitation above 5000 mm. The inland of Scandinavia Peninsula, the southeast of Iberian Peninsula, the southeast of Eastern Europe Plain and the coastal areas of Arctic Ocean are the areas with less precipitation in Europe, with annual precipitation below 400 mm and some areas below 200 mm, and the precipitation in mountainous areas is vertical.

2. As for the winter precipitation type, all parts of Europe (even southern Europe) can encounter snowfall, but except the northern and eastern parts of the line from the northern Caspian Sea to the southern Scandinavian Peninsula, the proportion of solid precipitation in other areas is less than 30%, and the snowfall in the British Isles, western France and southern Europe is less than one tenth of the annual precipitation (Figure 14).

3. Seasonal Distribution of Precipitation Most parts of Europe have precipitation all year round, and there is no obvious difference between dry and wet seasons, but it can still be divided into three regions: the annual precipitation distribution is uniform, mainly in summer and mainly in winter. In western Europe and northern Europe, the annual precipitation is almost evenly distributed, and there is a little more precipitation in winter due to frequent cyclone activities; In eastern northern Europe, central Europe and eastern Europe, due to the strengthening of continental nature, the maximum precipitation appears in summer months; Due to the influence of polar front and Mediterranean front cyclone activities in winter, the precipitation in southern Europe is mainly in winter, and the trend in the south is more obvious, and there is little precipitation controlled by anticyclone in summer.

Europe can be divided into the following six climate types.

(a) polar ice climate zone

The ice sheet climate exists only on the islands of the Arctic Ocean. It is controlled by the ice air mass all the year round, and the temperature is very low. In the hottest month, the average temperature is about 0℃, and the annual precipitation is about 200 mm. In the west of Spitsbergen Islands, influenced by the North Atlantic warm current, the climate is slightly mild, and the average temperature in the hottest month can reach about +5℃, and the precipitation can reach 300 mm.

(2) Polar tundra climate zone (polar long cold climate zone)

This area includes Iceland and the northern edge of continental Europe. The temperature here is low all the year round, and the landscape belongs to tundra zone and Forest tundra zone. In winter, the temperature in the west is higher than in the east. The average temperature in Leng Yue in Iceland's coastal area is around 0℃, in Murmansk's coastal area it is around -0.5℃ in June 5438+1October, and in Kanin-Bojola in the east it drops to around -20℃. In summer, the temperature is generally around 10℃, the growth period is very short, only 2-2.5 months, and even there is often frost in summer, so the climatic conditions are very unfavorable to agriculture. There is almost no farming operation here, and animal husbandry (mainly deer industry) is the main agricultural department here.

(3) sub-rigid coniferous forest climate zone (sub-rigid continental climate zone)

This area includes most of Fenos Candea and the northern part of Eastern Europe Plain. The latitude here is high, the winter is long, but it is rarely cold, and the summer is short and cool. The western coast of Scandinavia is controlled by polar ocean air mass all the year round, and the climate is maritime. In winter, the temperature is around 0℃ and there is abundant precipitation. From the east of Scandinavian Mountains to the Urals Mountains, the role of polar continental air mass and ice air mass is enhanced, the climate changes to continental, the winter is cold, and the temperature drops from west to east. In 65438+ 10, the average temperature in Gaffler is -4.4℃, in Petrozavodsk it is -9.9℃, and in Perm it is-15.4℃. Whenever an ice air mass invades, severe cold of -30℃ and -40℃ often occurs. It is usually cool in summer. The average temperature in July is 10- 12℃ in the north and 16- 18℃ in the south. The growth period is not long, usually 3-4 months. The growth temperature (above 10℃) suitable for rye, flax and vegetables in Eastern Europe lasts only 90 days at most, so the agriculture here is also underdeveloped.

The precipitation here is mainly related to cyclones. The annual precipitation in the western coastal areas exceeds 1000 mm, and the annual precipitation in other areas is 500-800 mm. The seasonal distribution of precipitation in the western coastal areas is relatively uniform, with a little more in winter and a little more in summer in the east. Besides cyclone precipitation, convective rain also accounts for a certain proportion.

(4) temperate maritime climate zone

This region includes the British Isles, France and western Central Europe, as well as the southern Scandinavia and the coastal areas of the Bay of Biscay in Iberia. The atmospheric pressure here is high in the south and low in the north all the year round, with a westerly wind, which is deeply influenced by the Atlantic air mass. Mild winter, cool summer, low annual temperature, more rain and less sunshine are the climate characteristics of this area.

The average temperature in June 65438+ 10 in this area is above 0℃. Rivers generally don't freeze. There is not much snowfall, generally it doesn't snow in the west, and the snow period in the east rarely lasts more than a week. However, when the Mongolian high pressure is very strong and the eastern polar continental air mass invades, it often leads to disastrous low temperature weather. Generally, the temperature is not high in summer The average temperature in July in the British Isles is 12- 17℃, and in the mainland it is 15-22℃. The temperature is lower in the north and higher in the south.

There are frequent cyclones in western Europe and more precipitation. The annual precipitation in the western part of the British Isles is above 1000 mm, and the coastal area in western Scotland can reach above 2000 mm. Other areas are mostly between 600-1000 mm. The seasonal distribution of precipitation is relatively uniform, with more in autumn and winter in the west and more in summer in the east. For example, Dublin accounts for 26% in autumn and winter, and 24% in spring and summer; Cologne accounts for 365,438+0% in summer, 25% in autumn, 23% in winter and 265,438+0% in spring.

(5) temperate continental climate zone

The region includes temperate continental humid climate and temperate continental semi-arid and arid climate. Generally speaking, Eastern Europe and Central Europe belong to the former, while Southern Europe and Eastern Europe belong to the latter.

The climate in eastern Central Europe has the nature of transition from maritime to continental. The influence of polar ocean air mass is dominant here all year round, with mild winter and low temperature in summer. The average temperature in 65438+ 10 is generally 0-4℃, which can reach -5℃ in a few areas, and the average temperature in July is generally around 18℃, which can exceed 20℃ in a few areas. However, ice air masses and polar continental air masses often invade, so the weather is very unstable. Precipitation is greatly influenced by topography, which is generally 500-600 mm in plain areas and more in summer.

The climate in eastern Europe is divided into two regions: the north and the south. The mixed forest belt in the middle is in the north, which belongs to the humid continental climate. It is greatly influenced by the polar ocean air mass. There is no severe cold in winter and the temperature will not be too high in summer. The average temperature in 65438+ 10 is between -5℃ and 14℃ in most areas, and the average temperature in July is less than 20℃. The annual precipitation is generally 500-600 mm, which is more in some areas. The southern region is located in the Eurasian high-pressure axis (called "Voyekov high-pressure axis" by the Soviets) and the area south of the high-pressure axis, and the related westerly airflow and cyclone activities are obviously weakened, and the anticyclonic weather is increasing. The annual precipitation is generally 300-500mm, the southeast is below 200mm, and the summer temperature is between 20-25℃. The water balance of the whole southern district is negative, belonging to temperate continental semi-arid and arid climate. In the natural landscape, most areas are grasslands, and the southeast is semi-desert or desert. Southern district is rich in heat resources and fertile land, and it is the main agricultural area. However, due to insufficient precipitation and great changes, droughts often occur.

(6) Mediterranean climate zone

This region includes most of Iberian Peninsula, French Mediterranean coast, Apennine Peninsula, most of Balkan Peninsula and various islands scattered in the Mediterranean. Mild and rainy winter and hot and dry summer are the main characteristics of the climate in this area.

Mediterranean climate is a unique climate type on the west coast of subtropical continent, and its formation is related to the change of air pressure situation in winter and summer and the movement of wind belt. The latitude of the Mediterranean region is just the transition zone of atmospheric circulation; The westerlies are in the north and the trade winds are in the south. In summer, the subtropical high moves northward. Under the control of azores high, the weather in the Mediterranean is sunny and dry. The average temperature in July reaches 24-28℃, and the highest temperature can reach 40℃. In winter, the subtropical high moved south, and azores high retreated to the Atlantic Ocean. The Mediterranean region is affected by the west wind, with frequent cyclone activities, more precipitation and mild climate, with an average temperature of 1 month.

The existence of the Mediterranean itself also plays a great role in the formation of the Mediterranean climate. Due to the large area of the Mediterranean Sea, a low-pressure lake is formed in the Mediterranean Sea in winter, which is conducive to the formation of the Mediterranean front, resulting in a series of cyclones, making the weather in the Mediterranean Sea particularly mild and rainy. At the same time, the higher Mediterranean water temperature also makes the coastal areas more temperate; In summer, on the contrary, the temperature in the Mediterranean is lower than that in continental Europe, and the air pressure is higher, which strengthens azores high and makes the Mediterranean region very hot and dry. In this way, the most typical subtropical climate in the world has been formed in the Mediterranean region, with warm winter, rainy summer and dry heat. Therefore, it is called "Mediterranean climate".

In the mountainous areas with the above climatic zones, the climate is more complicated. Because of the different heights, cutting conditions and slope directions of mountains, the climate changes greatly in a short distance. On higher mountains, the climate changes vertically.