How to judge seasons according to geographical phenomena

Judging seasons according to geographical phenomena: (The following seasons are subject to the northern hemisphere)

1. According to the revolution speed of the earth (or revolution position map)

At the beginning of 1 month, near the perihelion, the angular velocity and linear velocity of the earth's revolution are the fastest, and the winter half year is shorter; At the beginning of July, near the perihelion, the angular velocity and linear velocity of the earth's revolution are the slowest, and the summer half year is longer.

2. According to the change of sun altitude angle (or sun shadow) at noon.

Because the earth revolves around the sun in a cycle of one year, the direct point of the sun moves back and forth between the tropic of cancer, which causes the change of the height of the sun at noon. The greater the height angle of the sun, the shorter the shadow of the sun. For example, from the summer solstice (June 22nd), the direct sunlight is 23 26 ′ n, and the maximum area of the midday sun height angle is 23 26 ′ n, and the minimum area is within the Antarctic circle. At noon, the maximum area of the height of the sun reaches 23 26 ′ N, and the minimum area is south of the equator.

3. According to the change of the length of day and night (or polar extreme day and night conditions).

During the summer solstice (June 22nd), the longest day (24 hours) is in the Arctic Circle, the shortest day is in the Antarctic Circle, the longest day is in the northern hemisphere, and the shortest day is in the southern hemisphere. Generally, a day longer than 12 hours is a summer half year, and a day shorter than 12 hours is a winter half year.

4. Judging from the movement of the terminator line.

The height of the sun at all points on the finish line is zero, which divides the world into two hemispheres, day and night. Atmospheric scattering causes the actual range of the day hemisphere to be larger than that of the night hemisphere. As the earth rotates, the morning line moves westward and the dark line moves eastward (the speed is 15/ hour). In winter, the morning line in the northern hemisphere shifts eastward with the increase of latitude, and the dark line shifts westward with the increase of latitude; In the summer half year, the morning line in the northern hemisphere shifts westward with the increase of latitude, and the dark line shifts eastward with the increase of latitude.

5. According to the sunrise direction (or sunrise and sunset time)

The sun always rises in the east and sets in the west. The sun in the northern hemisphere runs in the sky in the southern hemisphere, and the sun in the southern hemisphere runs in the sky in the northern hemisphere. In the northern hemisphere, coming out from the northeast and setting in the northwest, the northern and southern hemispheres are the same; In the northern hemisphere, winter comes out from the southeast and falls in the southwest, which is the same in the northern hemisphere and the southern hemisphere. Sunrise in summer is earlier than 6: 00 local time and sunset is later than 18: 00. In winter, the local sunrise is later than 6 o'clock and the sunset is earlier than 18.

6. Control the rotation of the belt according to the movement of the position of the pressure belt and the air belt.

Because the direct point of the sun moves north and south with the change of seasons, the positions of pressure belts and wind belts on the earth also move with the change of seasons. For example, when the Mediterranean region is controlled by the subtropical high belt (or westerly belt), it can be judged that the season is summer (winter). The climate of savanna can be divided into rainy season (summer) and dry season (winter).

7. According to the ups and downs of land and sea pressure centers.

Because the specific heat of seawater is greater than that of land, the temperature change of seawater is much slower than that of land under the same solar radiation conditions. In summer, the temperature on the mainland is much higher than that on the sea, forming a low pressure; In winter, the temperature of the mainland is much lower than that of the sea, forming a high pressure. For example, when the high pressure in Hawaii is the strongest, it can be judged as summer.

8. From the bending direction of the sea-land isotherm

Due to the difference of thermal properties between land and ocean, the isotherm shows a regular curve. As shown on the right, in the northern hemisphere, in June of 438+ 10, the isotherm on the mainland protrudes southward (low latitude), while it protrudes northward (high latitude) on the ocean; July is just the opposite.

9. Judging from the direction of monsoon.

The phenomenon that the prevailing wind in a large area changes significantly with the seasons is called monsoon. In summer, the pressure in the mainland is lower than that in the ocean, and the pressure gradient points from the ocean to the mainland, so the wind direction points from the ocean to the mainland, forming a summer monsoon; In winter, on the other hand, the wind blows from the mainland to the ocean, forming a winter wind. Monsoons in the world are mainly distributed in East Asia, South Asia and northern Australia.

China's monsoon is influenced by East Asian monsoon in most parts of southeast China, and southwest monsoon and southeast wind in some parts of Yunnan-Guizhou Plateau. In winter, most parts of the country are affected by the mainland winter wind, which is cold and rainy; In summer, most parts of the country are affected by the summer monsoon from the ocean, which is hot and rainy.

10. Judging from the current trend of the North Indian Ocean.

The special ocean current system centered on the equator is affected by the seasons, and its flow direction changes. In winter, influenced by the northeast monsoon, the ocean current flows counterclockwise; In summer, influenced by the southwest monsoon, the ocean current flows clockwise.

1 1. According to climate characteristics and special weather phenomena.

The hottest month of climatic elements (July)-the most Leng Yue in summer (65438+ 10)-winter.

(Ocean August and February) Precipitation-Winter Rain-Mediterranean Climate-Summer Rain-Tropical Monsoon Climate, Subtropical Monsoon Climate, Temperate Monsoon Climate and Tropical Grassland Climate

Some special weather phenomena, such as spring drought in North China, plum rain in late spring and early summer in Jianghuai area, typhoon at the turn of summer and autumn in the southeast coast, summer drought in the middle and lower reaches of the Yangtze River, etc.

12. From the change of river flow,

The seasonal variation of river runoff is closely related to the water supply of rivers. Different types of rivers have different water sources, so the seasonal variation law of river runoff is also different.

(1) Rivers that mainly receive rainwater supply mainly change with the seasonal variation of rainfall. For example, in summer, the water volume of the Blue Nile reaches its maximum in a year.

(2) Rivers mainly supplied by ice and snow and meltwater from glaciers appear in summer. For example, the Tarim River appears in the flood season, which can be judged as summer (the maximum water quantity appears in August). Similarly, the month with the largest sea ice coverage around the Antarctic continent should be August-September.

(3) The flood season of ice and snow melt water supplying rivers appears in spring; If the Songhua River has the first flood season, it can be judged as spring; The second time was the frontal rain in August.

13. From the variation law of tropospheric thickness

It decreases from the equator (17-18km) to the poles (8,9km). In winter, convection is weakened and the thickness becomes smaller; In summer, the convection is strong and the thickness becomes larger.

14. From the salinity changes in some river estuaries,

The increase of river flow in flood season dilutes the salinity of seawater and reduces the salinity. For example, the salinity of the Yangtze estuary gradually increases from the estuary to the outside, the isobar contracts to the estuary in winter, and the salinity of the same sea area increases; In summer, the isobar extends to the open sea, and the salinity in the same sea area decreases.

15. From the height of the snow line,

Snow line is the lower limit of snow cover for many years, and it is the balance zone of annual snowfall and snowmelt. From low latitude to high latitude, the height of the snow line in the mountain gradually decreases, and the position of the snow line changes obviously with the seasons. Due to the high temperature in summer, the ice and snow at low altitude melt and the snow line is high. It's lower in winter. Of course, marine glaciers are also affected by precipitation.

16. From the perspective of vegetation change,

Because the growth and development of plants are affected by natural factors such as heat and water, these natural factors change with the seasons, resulting in obvious seasonal changes in vegetation. For example, the tropical grassland climate zone is alternately controlled by the equatorial low pressure zone and the trade wind zone, and the dry and wet seasons alternate obviously. When there is plenty of rainfall in summer, the vegetation is lush, and when there is little rainfall in winter, the vegetation is yellow.

17. From the law of animal activities,

Reindeer migrate from northern tundra zone to coniferous forests south of tundra zone in autumn to escape the cold in winter, and return in summer to avoid the invasion of mosquitoes in coniferous forests. For another example, when the red-crowned cranes gather in Yancheng Nature Reserve in Jiangsu, it is winter and Zhalong in Heilongjiang in summer; Australian kangaroos give birth in winter; In autumn, geese in China fly south.

18. From the perspective of agricultural activities

Agricultural production activities are regional, cyclical and seasonal, including fishery and animal husbandry. For example, picking new tea in the hilly areas of the south of the Yangtze River is spring; Zhoushan fishing ground has more fish in winter and more squid in summer; "Alpine grazing" in Tianshan Mountain is in alpine pasture in summer and in foothills pasture in winter, that is, "mountainside in summer and foothills in winter"; Autumn cotton harvest in North China Plain.

19. According to the size of the ozone hole.

The minimum distribution area of ozone is easy to appear in the lower troposphere, such as the Qinghai-Tibet Plateau, the North Pole and the South Pole. From September to165438+10, the ozone distribution in the Antarctic has a minimum value. From March to May, the minimum ozone distribution appeared in the Qinghai-Tibet Plateau and the Arctic in the northern hemisphere.

20. Others

(1) Spring: The salt drying period in Luchang salt area is favorable, the North China Plain is dry, wheat is planted to the north of the Great Wall, and there are strong winds or sandstorms in the north.

(2) Summer: the best season to visit the Arctic, the countries along the Mediterranean Sea are hot and dry; There is a cold current along the coast of Somalia.

(3) Meteorological disasters in China: frequent cold waves, sandstorms, droughts and blizzards in winter; There are many droughts and floods, rainstorms, typhoons, hail and dry hot winds in summer.

(4) The best bird watching opportunity in Qinghai Lake in May (flying to Bird Island in April, spawning and hatching in May, and flying away in late June).