What are the special geographical and climatic phenomena in Zhejiang? What are the advantages and disadvantages of these phenomena?
Topography: The topography of Zhejiang Province is stepped from southwest to northeast. In the southwest, there are many mountains whose distance exceeds 1000 meters. Among them, Huangmaojian Peak in Longquan City is the highest peak in the province, with an altitude of 1.929 meters. The terrain is dominated by hills and mountains, accounting for 70.4% of the total area of the province. The main mountain ranges from north to south are Huaiyu Mountain, Tianmu Mountain and Kuocang Mountain. The plain area accounts for 23.2%, mainly including Hangjiahu Plain, Ningshaoping Plain and Huangwen Plain. The basin is mainly Jinqu basin. The area of rivers and lakes in China accounts for 6.4%, including Qiantang River, Oujiang River, Caoejiang River, Lingjiang River, Shaoxi River, Feiyunjiang River, Yongjiang River and Aojiang River. In addition, there are the Grand Canal, West Lake in Hangzhou, South Lake in Jiaxing, East Lake in Shaoxing, Dongqian Lake in Ningbo and Qiandao Lake (namely Xin 'anjiang Reservoir). The total length of Zhejiang coastline is more than 6,400 kilometers, ranking first in the country. There are more than 3,000 coastal islands with a continental shelf area of 230,000 square kilometers within 200 meters.
Hydrology: rivers are rich in water, and the annual runoff of surface water is more than 90 billion cubic meters.
Soil: The soil is mainly yellow soil and red soil, accounting for more than 70% of the province's area, mostly distributed in hills and mountains, mostly paddy soil in plains and river valleys, and mostly saline soil and desalted soil along the coast.
Climate: The climate in Zhejiang is characterized by obvious monsoon, distinct seasons, moderate annual temperature, abundant sunshine, humid air, synchronous changes in rainy and hot seasons, diverse allocation of climate resources and numerous meteorological disasters. The annual average temperature in Zhejiang is 15 ~ 18℃, the extreme maximum temperature is 33 ~ 43℃, and the extreme minimum temperature is -2.2 ~- 17.4℃. The average annual rainfall in the province is 980 ~ 2000mm, and the average annual sunshine hours are1710 ~ 2100h.
In spring, the East Asian monsoon is in the alternate season between the winter wind direction and the summer monsoon. The north-south airflow frequently meets, and the low pressure and frontal activity intensify. The climate in Zhejiang in spring is characterized by cold and rainy weather, frequent coastal and offshore winds, more rain in the whole province and uncertain weather. As the saying goes, "three faces change in spring." The average temperature in spring in Zhejiang is 13 ~ 18℃, and the temperature distribution is decreasing from inland areas to coastal and island areas. The precipitation in the whole province is 320 ~ 700 mm, and the distribution of precipitation gradually decreases from southwest to northeast coastal areas; The rainy days in the whole province are 4 1 ~ 62 days. The main meteorological disasters in spring are rainstorm, hail, strong wind and low temperature in late spring.
In summer, with the establishment of the summer monsoon circulation system, the southeast wind prevails in Zhejiang, and the subtropical high activity in the northwest Pacific has an important influence on the weather in Zhejiang, while the cold air from the north to the south still has a certain influence on the weather in Zhejiang. In the early summer, all parts of Zhejiang have entered the flood season one after another, commonly known as the "Meiyu" season, and the probability of heavy rain and heavy rain increases, which is easy to cause floods; In midsummer, affected by subtropical high, Zhejiang is prone to sunny, hot and rainy weather, leading to drought; Summer is the period with the greatest probability that tropical storms will affect Zhejiang. The summer climate in Zhejiang is characterized by high temperature, abundant precipitation, strong illumination, humid air and frequent meteorological disasters. The average summer temperature in the whole province is 24 ~ 28℃, and the temperature distribution is decreasing from the central area to the surrounding areas. The precipitation is 290 ~ 750 mm in various places, with more precipitation in eastern mountainous areas, such as Kuocang Mountain, Yandang Mountain and Siming Mountain, and less precipitation in islands and central areas. It rains for 32 to 55 days in all parts of the province. The main meteorological disasters in summer are typhoon, rainstorm, drought, high temperature, thunderstorm, strong wind and tornado.
In autumn, the summer monsoon gradually weakens and transitions to the winter monsoon. Cyclone activity is frequent, frontal precipitation is more, and temperature changes greatly. Characteristics of autumn climate in Zhejiang: in early autumn, Zhejiang is prone to intermittent rainy weather, commonly known as "autumn Lasha"; Mid-autumn, controlled by the high-pressure weather system, Zhejiang is prone to high-sky, light-cloud and sunny autumn weather, which is called "Koharu in October"; In late autumn, the influence of cold air in the north began to increase, and the conversion process between cold and warm weather and sunny and rainy weather was frequent, and the temperature fluctuated greatly. The average autumn temperature in the whole province is 16 ~ 2 1℃, with high temperatures in the southeast coastal and central areas and low temperatures in the northwest mountainous areas. The precipitation is 2 10 ~ 430mm, with more precipitation in the central and southern coastal mountainous areas and less precipitation in the northeast, but its interannual variation is great. It rains all over the province for 28 ~ 42 days. The main meteorological disasters in autumn are typhoon, rainstorm, low temperature, rainy weather and fog.
In winter, the strength of winter monsoon in East Asia mainly depends on the activity of Mongolian cold high pressure, while the weather in Zhejiang is affected by the cold air mass in the north (that is, winter monsoon), and there are relatively few types of weather processes. The winter climate in Zhejiang is characterized by abundant sunshine, cold and little rain, and dry air. The average winter temperature in the whole province is 3 ~ 9℃, and the temperature distribution is decreasing from south to north and from east to west. Precipitation 140 ~ 250 mm, except for the northeast islands, there is little difference in other places; The rainy days in all parts of the province are 28 ~ 4 1 day. The main meteorological disasters in winter are cold wave, freezing injury, strong wind, heavy snow and fog.