Who knows the interesting weather in China?

On the evening of July 5, Penglai, Shandong Province, which is famous for its mysterious "mirage", once again appeared wonders. A clear "mirage" appeared on the sea, making people confused whether it was heaven or earth. More than10,000 people on the beach are full of eyes. It is said that the mirage in the evening is not recorded in the local chronicles.

Penglai was called "Dengzhou" in ancient times, and Dengzhou Haicheng has been concerned by people from all walks of life since ancient times. It is well known that Qin Shihuang sent Xu Fu to lead 3,000 boys and girls to the sea, seeking "Penglai Elixir" and "Penglai Immortal". "Historical Records" said: "It was spread in the Bohai Sea, not far from people, but if it came, the wind would lead it away. Those who cover the taste are the best, and the fairy medicine is in the clouds. Their beasts and beasts are all white, and gold and silver are palaces. " Emperor Wu of the Han Dynasty also toured Penglai many times, in order to find a trace of immortality, so as not to be old in the world. However, there is no doubt that both emperors and generals and ordinary people returned empty-handed. Wonderland of God always flies away when they come not far from Wan Li. "No, it looks like a cloud; As far as I know, Sanshen Mountain lives underwater; When you get close, the wind will lead you, and you will never get there. "

Even so, people still can't explain everything they see. Therefore, for hundreds of years, countless scribes and poets have boarded the pavilion to chant about Haicheng or seek longevity, making Penglai famous all over the world. It was not until the Ming Dynasty that a talent named Lu Rong made a scientific explanation of the sea market in Miscellanies of the Garden: "The so-called sea market is mostly composed of mountains and rivers."

So, what is this "fairyland on earth" that people have been chasing for thousands of years? Recently, the reporter visited Xue Hao, a researcher at China Institute of Meteorological Science.

In order to explain clearly to the reporter, researcher Xue specially drew a schematic diagram. He said that Haicheng is an atmospheric optical phenomenon, which is caused by the abnormal distribution of atmospheric density caused by severe temperature gradient, and the obvious refraction or total reflection of light when it passes through air layers with different densities. Sea cities generally occur in coastal areas, snowfields, deserts and polar regions, and are divided into Shanghai, Shanghai and Binhai. Sometimes, due to strong turbulent activities, complex mirage will appear.

He said that in summer, on the calm water surface, the upper air is very hot and the density is low, and the air near the water surface is affected by the current, so the temperature is low and the density is high. When the temperature difference between the upper and lower air layers is large and the density is different, the light reflected from the surrounding islands, towns, ships and other scenery on the horizon can appear upright images through up and down refraction or total reflection. On land, especially in desert areas, because the sun is shining in the sky during the day, the ground is heated strongly, the air near the ground is heated quickly, the ground is hot and the sky is cold, and the light below is refracted upwards, so the scenery is inverted. If two layers of air with different densities are parallel, a side mirage can also appear. Due to the turbulence of the air layer, the scenery appears to be large and small, intermittent and flickering, giving people a mysterious and changeable feeling.

Now we can proudly say to our ancestors that Haicheng is beside us. It is a true reflection of real things in life, a beautiful gift from nature to human beings, and it is by no means a so-called fairyland. With the changes of the times and the development of society, Haicheng is also contaminated with modern flavor. The scenery of Haicheng has already changed from "palaces, terraces, city walls, figures, chariots and horses, and crowns" recorded by the ancients to rows of urban buildings and wide urban streets today.

It is understood that the sea market has also appeared in Qingdao, Hangzhou, Quanzhou and other places in China, but it appears frequently in Penglai. This is determined by Penglai's unique geographical location, hydrological conditions and climatic conditions. Penglai is located in the southern promontory of Bohai Strait, facing Liaodong Peninsula and Korean Peninsula across the sea, and Changshan Islands are located between the straits, which provides various reflective scenery with different distances for the appearance of the offshore market. However, when there is a high tide in this area, the surging current in the strait takes the bottom seawater out of the low-temperature water surface, which makes the surface temperature of seawater far lower than that of air-sea surface, and it is easy to form the inversion phenomenon that the air-sea temperature rises sharply from bottom to top and the density drops sharply. Because geographical location and hydrological conditions are constant and relatively stable, climate conditions are even more important. Sun, director of Penglai Meteorological Bureau, introduced the weather conditions when the sea market occurred on July 5: the highest temperature on July 5 was 26 degrees Celsius, and the lowest temperature was 19.7 degrees Celsius. The visibility is good all day, the relative humidity is 80%, and the average wind force is 2.8 meters per second. He said that the sea market often appears in summer or at the turn of spring and summer. In recent years, the records of Penglai sea city show that the general weather conditions have the following characteristics: moderate temperature, sunny or partly cloudy, northerly winds of Grade I and II, and high visibility at sea. The weather on the 5th basically conforms to the previous characteristics.

Due to the uncertainty of various factors, the appearance of Penglai sea city is erratic, unpredictable and unpredictable, and many tourists who come here are excited and leave one after another. Director Sun also told reporters with regret that when he was told by his friends that he was driving there, there was only a long fog line in the sky, and the scene was already blurred. At this point, director Sun, who was born and raised in Sri Lanka, still missed a glimpse of the "beauty" of Shanghai. Fortunately, Sun Yuping, a reporter from Shandong TV Station, captured the mirage on June 7 1988 with a video camera, and grasped the fleeting beauty, so that it can be shared with more people who love nature and are eager to explore its mysteries.

The fun of ice and hail

1987 March 15, a villager came to a waste collection station in Zhangcha, feeling the joy of treasure hunting on the ground, and put an item on the scale for trading. I saw that the "treasure" was the size of a teapot, shaped like a pebble and crystal clear. I don't know what it was. Shocked and embarrassed, the staff at the acquisition station explained to the customer that they could not buy it, but the customer insisted on selling it. During the verbal debate, the "treasure" gradually shrank and became smaller until it disappeared completely, leaving only a pool of colorless and tasteless liquid on the scale, and the business naturally ended. This incident was passed down as a joke in rural neighborhoods for a while. After verification, hail appeared in the suburb of Foshan at noon on March 13, with a diameter of about 3 cm. According to the weather background, the characteristics of the "treasure" and the melting phenomenon, it is inferred that the "treasure" should be a rare hail. There have been many hail disasters in the South China Sea in history, which are recorded in Nanhai County Records, such as: "In February of the eighth year of Qing Shunzhi (165 1), the rain was as heavy as a bullfight, houses collapsed and livestock died."

Huang Yu

In Xing 'anling area of China, it rains strangely from May to June every year. In fact, it is the result of dyeing pine pollen. Because during this period, when the pine blossoms are in full bloom, the yellow pollen and water vapor over the sea are stuck together and become "yellow rain". On February 1870 and 14, Genese also had an "apricot rain". Chemist Castela made a chemical analysis of the rain and found that it contained 6.5% water, 6.6% nitrogen-containing organic matter, 65.5% sand and clay, and other substances such as iron oxide and calcium carbonate. In fact, the "apricot rain" was caused by a tornado that rolled the yellow mud on the ground into the sky and mixed it with the rain.

Snowy weather in the South China Sea

If citizens in the South China Sea intend to appreciate the snow, their first thought is to go to the north. In this land of the South China Sea, people generally have no impression of snow. Nanhai city is located in the subtropical zone, and the temperature is high, so it is really difficult to have the meteorological conditions for snow. However, occasionally there will be a particularly strong cold wave invasion, and it will snow in the South China Sea. According to Nanhai County Records, since the Song Dynasty, there have been 13 snowfalls, the next snowfall will average more than 50 years, and the latest snowfall will be 1929. Please look at the snow situation recorded in detail in Nanhai County Records several times:

In December of the fifth year of Chunyou in the Song Dynasty (1early 246), it snowed for three days and accumulated more than a foot, which was unprecedented.

In the 13th year of Yongle in Ming Dynasty (14 15), plum blossoms died in winter snow.

In the third year of Qin Long in the Ming Dynasty (1569), it snowed heavily in Xiqiao Mountain in December, and all the trees were frozen, which was solved the next day.

In the 22nd year of Emperor Kangxi of Qing Dynasty (1683), all the trees died in winter due to heavy snow and frost.

In the fifteenth year of Qing Daoguang (1835), there was heavy snow all over the sky on December 22nd, covering more than four inches.

In the third year of Guangxu reign in Qing Dynasty (1877),10/29th of the month, wind, rain, thunder, snow and hail came together, and many fish froze to death.

On November 17th and 18th (beginning with 1893) in the 18th year of Guangxu reign in Qing Dynasty, there was a heavy snow, and there was more than one inch of snow on the ground.

Since the winter of 18 (1929) in the Republic of China, the weather has been unusually warm and it hasn't rained for a long time. It began to rain lightly on the 27th, and the north wind blew hard in the early morning of the 29th, and it turned to light snow at dawn. It was rather cold after dawn. It was still snowing on the morning of the 30th, and it was even colder in the afternoon. Plum blossoms and red chrysanthemums in Central Park (in Guangzhou, when Nanhai County was stationed in Guangzhou) were covered with snow flies, all bright white. 3 1 in the morning, the snow is still falling, and the degree of cold is particularly fierce. Cha is the morning of Panfu Road, where a 20-year-old beggar was found dead on the ice.

It seldom snows in the South China Sea, but it is not impossible. Climate change is cyclical. In recent years, the temperature is on the high side and it is in a warm period. When the cold period comes, the chance of snow will increase. People should be alert to this.

The evil of plum rain

It rains at home in Huangmei season, and frogs are everywhere in the grass pond. "The breeze blew the fields green, and the plum rains filled the fields." Plum rains, year after year, nourish the vast fertile fields in the south of the Yangtze River and bring vitality to everything. However, what Meiyu brings is not all described above, but a colorful picture of early summer customs in the south of the Yangtze River, a gratifying scene of exultation of rivers and vigorous seedlings. That abnormal plum rain (such as empty plum rain or long plum rain) will bring serious drought and flood disasters to the middle and lower reaches of the Yangtze River.

Meiyu refers to the continuous rainy weather in the middle and lower reaches of the Yangtze River in China (including South Korea and southern Japan) during the transition from early summer to midsummer every year. Under normal circumstances, the rainy season lasts about 20-30 days, starting in mid-June and ending in mid-July, and the rainfall is generally 200-400 mm.

During the period of 1954, the extraordinary flood in the Yangtze River valley in China was caused by unusually long plum rains. This year, God seems to have a mental illness, and his brain is out of control. All day long, he was unhappy, with light rain, heavy rain and heavy rain. Meiyu came early this year and "entered Mei" in early June; I left late and didn't "blossom" until early August. For two whole months, plus the spring rain in May, the precipitation in the middle and lower reaches of the Yangtze River during this period exceeded that in the past year, leading to flooding. During the whole flood season, there were 2 1523 dangerous incidents on Jianghan levee in Wuhan, which happened once in less than 10 minutes on average. The highest water level in Wuhan is 29.73 meters. In order to defend Wuhan, the floodgates were opened three times to discharge water into Jingjiang flood diversion area, with a total flood volume of12.256 billion cubic meters, which made more than 20 flood diversion and storage areas from Zhijiang to Hubei and Xiangyang to Dongxihu in Hankou saturated or even supersaturated. Due to the flood, more than 6 million people were transferred in Hubei, Hunan and Jiangxi, and the Beijing-Guangzhou Railway 100 day could not be opened to traffic normally.

In some years, plum rains are very inconspicuous. Like a passer-by in a hurry. It stays in the middle and lower reaches of the Yangtze River for ten days or even a few days, and then goes north. Moreover, there is not much rain during the stay, and it is rare to have one or two heavy rains. This situation is called "less plum" or "empty plum". The evil result it caused is just the opposite of the waterlogging caused by the extremely heavy plum rain, but the drought caused by cracking the ground.

During 1978, the rainy season ended in just seven days, and the rain was so weak that it was difficult to see the misty rain in ancient Jiangnan. Wan Li is clear, the sun shines directly on the earth, and the high temperature and low humidity caused a rare drought in the 20th century. The two "arteries" of the Yellow River and the Yangtze River have obvious symptoms of anemia, which directly affect the economic belt along the Yellow River and the Yangtze River. The drought-affected areas of these two economic zones 16 provinces and regions reached 290 million mu. The drought affected North China, the eastern northwest, the northeast and the southwest, causing great losses to agriculture. More than 7 million mu of farmland along the middle and lower reaches of the Yangtze River died, the planting area of double-cropping late rice in Hubei and Anhui provinces decreased by more than 6.5438+million mu, and the autumn grain crops in Shanxi died of drought by 3 million mu. This also makes the water use of people and animals a problem. Nearly 2 million people in two lakes and three provinces in Jiangxi have difficulty drinking water.

The weather in Beijing is favorable for the Olympic Games.

Beijing is located in the east of Eurasia, surrounded by mountains in the west, north and northeast, and 0/50 km away from Bohai Sea/KLOC in the southeast. It belongs to the continental climate of humid monsoon in the south temperate zone and has the characteristics of distinct seasons. The average annual precipitation is 565. 1 mm. The main meteorological elements during the Olympic Games are as follows:

(1) Temperature and humidity. According to (1990- 1999) statistics, during the Olympic Games, the average daily temperature in Beijing was 24.5 ~ 26. 1℃, the average maximum temperature was 30.8℃, the average minimum temperature was 22.3℃, and the average daily temperature difference for many years reached 8.5℃. The highest temperature appears in the afternoon and lasts for a short time. The diurnal variation of humidity is just the opposite of that of temperature. The highest temperature and the lowest humidity appear simultaneously, and the lowest temperature and the highest humidity appear simultaneously. This temperature and humidity configuration makes people feel comfortable and suitable for outdoor activities.

(2) precipitation. During the Olympic Games, it was mostly precipitation. According to statistics, in the 20 days from late July to early August, the number of precipitation days with daily precipitation greater than 1 mm is only 6 days, and the precipitation duration is short, which will not have a great impact on outdoor competitions. This kind of precipitation often brings cool and fresh air to Beijing in summer.

(3) Wind direction and wind speed. The wind direction in Beijing is obviously influenced by the terrain. Under normal circumstances, it is mostly 2 ~ 3 southerly winds during the day and 1 ~ 2 northerly winds at night. During the Olympic Games, there were few strong winds. Winds greater than level 4 are often accompanied by precipitation, and the time is very short.

During the Olympic Games, the weather in Beijing is good, the temperature is not too high during the day, and it is cool at night, which is conducive to rest. During this period, there is little special weather in Beibing that affects the competition. The probability of sandstorm and tornado is 0, the probability of hail is only 0.3%, the probability of fog in daytime is 1.6%, and the probability of gale and rainstorm is very low, which are 2% and 4% respectively. It can be seen that the special weather may have little impact on the Olympic Games. In addition, according to the analysis, during the Olympic Games, Beijing has the lowest annual inversion probability and the strongest annual atmospheric self-purification ability. According to the measurement, the air quality in this period is the best in the whole year, which is conducive to outdoor activities and sports competitions.

Desert amorous feelings painting-another perspective of barren land

At the beginning of the new century, the word "sandstorm" frequently appeared in newspapers. As we all know, the main source of sandstorm is desert. Speaking of desert, in people's imagination, it is a yellow barren land, full of bleak and desolate atmosphere.

However, the deserts in the world are not the same grayish yellow. Some of them are colorful under the sunlight and even become a tourist area.

The desert of Arizona, where the Colorado Grand Canyon is located, is very attractive to tourists because of its "dyeing" with various colors, and has been opened up as the desert park. On the surface, this desert is sand-free, full of sand and stones containing ancient volcanic lava minerals. Because the local temperature changes greatly, it can be reduced from 4 1℃ to MINUS 30℃, and the weathering is very strong. Over the years, layers of sand are crystallized and mineralized, with various colors such as purple, yellow, red, green, white and blue, as if it were a huge plate inlaid with precious stones. Under the sunshine, it is dazzling. Under the action of steam, these colors will condense into various colors of smoke and shine, which is really wonderful and magical.

White Desert There is a strange white desert in the Rusuluo Basin in New Mexico, USA. Overlooking from the air, hundreds of kilometers around presents a silvery white world, except for a few plants firmly rooted in the sand sea. More interestingly, some animals here, such as marsupials, lizards and several insects, have turned white in order to adapt to the harsh environment. These "angels in white" appear from time to time, which makes people feel like they are in a fairy tale world. Stranger still, in the morning sun or sunset glow, the desert becomes a huge mirror, which breaks down the sunlight into red, orange, yellow, green, cyan, blue and purple, just like a rainbow after rain. It is said that the cause of the white sand dunes is that the gypsum seabed changed several times more than 100 million years ago, and the gypsum mine crystallized into white tiny particles after years of weathering, thus adding this romantic style to this desert.

The Black Desert The Karakum Desert in the former Soviet Union and Central Asia is dark brown, boundless and gloomy. When tourists come here, they often arouse nostalgia for the past or feel a little shudder. According to the investigation, the sand in Karakum Desert is often weathered by the black rocks here.

Red Desert The Simpson Desert in Australia is red, especially under the sunlight, and heaven and earth are inseparable. Red is muddy and extremely magnificent. Like rain, small plants sprout and bloom, and "a little green among red flowers" adds splendor. The mystery of the desert turning red turned out to be the long-term weathering of iron minerals, which covered the sand with a layer of iron oxide.

It is not difficult to see that whether it is a colored or red desert or a white or black desert, it is formed by the long-term weathering of the rocks on the ground, but the texture of the rocks is different, but the world is mainly yellow desert. Although the desert has been described by scholars as a barren land in forever dead, nature has left an unfortunate place for human beings. In the vast desert area, sand flying with the wind accumulates on the ground, forming various sand dune patterns. From a distance, it looks like an endless undulating sea, but the blue sky and yellow sand are closely linked, and this pattern is constantly changing. Some dunes are like pyramids, with four corners and a sharp spire on four slopes. The patterns carved by the wind make people daydream and can't help but attract people to appreciate the ever-changing "customs" of the desert. There is a desert singing style here.

Xiangshawan in Inner Mongolia has become a famous tourist attraction at home and abroad. People grabbed a handful of golden sand and threw it down hard. The sand made a "wow". People climbed to the top of the sand dune along the sand slope and fell from the top, and then there was a "buzzing" sound at the foot of the sand mountain, as if someone were fiddling with the strings. If you keep pulling the sand down with your hands, but you see the sand rushing to the foot of the mountain like running water, there will be a loud noise, like the sound of several planes hovering in the sky. In addition to Xiangshawan, there are Mingsha Mountain in Dunhuang, Gansu, Xiangsha Mountain in Zhongwei, Ningxia and Mingsha Mountain in Bakun County, Xinjiang. There are more than 100 singing dunes in the world. What is even more bizarre is that there is a big sand dune on the southwest coast of Kauai Island in the Hawaiian Islands, which is 800 meters long and 18 meters high. When people walk on the sand dunes, the sand will bark like a "barking dog". If you put the sand in the palm of your hand, it will make the same sound. In fact, Sasha Vujacic is a natural phenomenon. According to scientists' speculation, a thin air film may be formed on the surface of sand dunes soaked by rain or seawater during water evaporation. Due to the vibration caused by human movement, sand will make a sound. But the reason that really makes the sand dunes make noise is still unclear.

Interpretation of summer heat index

Heatstroke, commonly known as rash. It is dizziness, dizziness, palpitation and other symptoms caused by long-term exposure to the sun in summer, or working in other high-temperature environments. In severe cases, it may even cause temperature rise, fainting or spasm. It is a common disease in medical emergency in summer. It mainly occurs in central and southern China, especially in the middle and lower reaches of the Yangtze River. With the intensification of climate warming and the development of urban construction, the occurrence of heatstroke has gradually developed to large and medium-sized cities in northern China. 1997 during the hot summer weather, heatstroke occurred in large and medium-sized cities in North China, Northwest China and Northeast China to varying degrees.

Heatstroke is a kind of heatstroke, which is divided into three grades by the medical department: threatened heatstroke, mild heatstroke and severe heatstroke.

Threatened heatstroke: After working in a high-temperature workplace for a certain period of time, symptoms such as headache, dizziness, thirst, sweating, general fatigue, palpitation, inattention, and uncoordinated movements appear. The body temperature is generally normal or slightly higher.

Mild heatstroke: In addition to the aggravation of the symptoms of threatened heatstroke, there are flushing, excessive sweating and rapid pulse. The body temperature rises above 38℃.

Severe heatstroke: There are three symptoms. (1) suddenly became ill in a high temperature environment, with a body temperature above 40℃, and began to sweat a lot, followed by "anhidrosis", accompanied by dry skin and different degrees of consciousness disorder. (2) There are mainly obvious muscle spasms accompanied by contraction pain, which occur symmetrically in the muscles of limbs and abdominal muscles with more activities, and sometimes attack and sometimes relieve. At this time, the patient's consciousness is clear and his body temperature is normal. (3) Acute onset, headache, dizziness, sweating and thirst, nausea and vomiting, cold skin, decreased blood pressure, arrhythmia, mild dehydration, but low body temperature.

Heatstroke is a great threat to human life, and the mortality rate of severe heatstroke is high. According to the statistics of Jiangsu Meteorological Observatory, during the four years of 1988, 1994, 1995 and 1998, there were as many as 10000 people suffering from heatstroke in Nanjing, including nearly 1,000 people suffering from severe heatstroke, and the mortality rate of severe heatstroke was 30.2% respectively.

It is not difficult to see that the occurrence of heatstroke is closely related to high temperature. In the hot weather with the daily maximum temperature above 35℃, the number of heatstroke patients will increase significantly. Heatstroke is also related to air humidity. If the humidity is too high, even if the temperature is lower than 35℃, some people will suffer from heatstroke. After research, the Medical Meteorological Research Group of Jiangsu Meteorological Observatory defined three levels of heatstroke index with the three-day moving average temperature of 30℃ and relative humidity of 73% as indicators, and also calculated the meteorological condition index of heatstroke in detail. As far as Nanjing is concerned, in general, from late June to September, that is, from the late Meiyu (or plum blossom) to the high temperature of autumn tiger, Jiangsu Meteorological Observatory issued early warning and forecast of heatstroke to the general public through radio, newspapers and other media. In addition, they also actively carry out professional meteorological services and transmit heatstroke index forecasts to factories, mines, hospitals and emergency centers by telephone, fax and internet. Based on this, people can do a good job in heatstroke prevention and cooling. Especially after three days of high temperature, everyone should pay special attention. For different people, prevention methods are different:

1. The elderly and infirm: First, reduce going out and avoid activities in the scorching sun. Their living environment should be ventilated, ensure sleep, drink salty water and eat digestible food.

2. Infants and young children: Its prevention is particularly important, mainly to avoid clothes being too warm and thick, and to do more cold-resistant exercise.

3. Maternity: It is necessary to break the stereotypes, scientifically confinement, and regularly open the bedroom doors and windows for ventilation every day. Mom should not "hide", wash her hair and bathe to clean her skin.

4. Outdoor workers in high temperature: usually take thermal acclimatization exercise, reasonably arrange work and rest time, improve working conditions, and drink more salty boiled water, herbal tea and mung bean soup. Prepare some heatstroke prevention drugs in the workplace, such as Ren Dan, cooling oil and ten drops of water. If you feel sweaty, dizzy and your heart is racing, you should finish your work quickly and move to the shade to have a rest.

If the above-mentioned personnel have premonition or mild heatstroke, they should immediately leave the high-temperature environment, rest in a cool and ventilated place, take Ren Dan, Shidishui and other traditional Chinese medicines for relieving summer heat, and apply cool oil and wind oil essence on their foreheads and people. It is best to go to the hospital to hang water for treatment. If severe heatstroke occurs, physical cooling should be taken immediately. Ice packs or cold wet towels should be placed in the aorta and soaked or cleaned in water at 25℃. However, it is forbidden to wash the precordial area, so as not to induce cardiac arrest, and the elderly and infirm can only scrub with alcohol. No matter who has severe heatstroke symptoms, they should be sent to the nearest hospital for emergency treatment immediately to avoid death.

"Red Ghost" is making trouble in the East China Sea

On May 9, a large-scale red tide broke out in the sea area east of Chenda Island in Taizhou City, Zhejiang Province. The red tide started from the East Pole in the north and reached Yankee Island in the south. The red tide water body is reddish brown, continuously distributed in an arc strip shape, about 25 nautical miles long and 6 nautical miles wide, with a total area of 500 square kilometers. A boatman in Jiaojiang said: "Our ship found a large area of Niulan water (red tide) about 15 nautical miles southeast of Yankee. At night, when the ship passes by, it is blue and bright. " Jellyfish disasters occurring at the same time as red tides also pose a threat to local marine fisheries. A large number of jellyfish appeared in Yuhuan County, not far from the red tide. Due to the invasion of jellyfish, more than 0/00 local fishing boats have to dock to fish, and the loss of each fisherman is more than100000 yuan.

In recent years, the "red tide" off the coast of China frequently appeared in newspapers. What is red tide, and why does it attract so much attention from the news media? In fact, red tide mainly occurs in offshore waters, which is a phenomenon that the water color changes due to the explosive proliferation or aggregation of some plankton in the waters. Red tides are not all red, in fact, they are all kinds of color tides, and the colors of red tides caused by different red tide organisms are also different.

What is the impact of red tide on fishery production and marine ecological environment? Recently, the author visited Taizhou fishery administration and aquatic products department with these questions. According to the statistics of Taizhou Fisheries Bureau, on June 10, 2000, red tide caused a large area of fish, shrimp, crab and shellfish cultured in Taizhou shallow sea to die. The damage value of fish and cockroaches in Taizhou Road and Bridge in Cangnan, Wenzhou and some harbors is more than 1 1 10,000 yuan; The outbreak of Sanmen shrimp disease caused a loss of more than 5 million yuan; The high ponds in Linhai City can't receive water, which brings difficulties to the normal aquaculture production ... And since this year, "red ghost"-red tide has appeared in many places along the coast of China, not just Taizhou, which has aroused great concern.

Chen Zhiliang of Taizhou Fishery Environmental Monitoring Station said: "During the process of mutation and reproduction, red tide organisms cause a large area of anoxia in water, which can suffocate and kill marine organisms, among which toxic algae will discharge toxins and poison marine organisms. In addition, the dead red tide organisms sink to the bottom of the water, and after decay, they produce toxins that cover the bottom of the sea, which can lead to the death of benthos. The boatman said that you can't catch fish in such waters because almost all the fish and shrimp are dead. After the discovery of red tide in Taizhou waters, the fishery administration department entered a state of readiness and released red tide news in time to avoid aquaculture losses. "

Cheng of Taizhou Fisheries Bureau pointed out that the appearance of this red tide should not be taken lightly. Taizhou is a developed fishery area in central Zhejiang, and the outbreak of red tide may cause fatal damage to fishery. In fact, every red tide will cause different degrees of damage to the marine environment. The cause of red tide is a difficult problem in the world ocean research. Experts have conducted in-depth research on red tide, and believe that the causes and mechanisms of red tide formation are very complicated, but it is generally believed that the existence of red tide organisms and eutrophication of water bodies are the basis of red tide formation. Cheng said: "The main reason of red tide is that the ocean is too eutrophic. With the development of Taizhou industry, especially the increase of chemical plants along the river, some discharged organic matter enters the ocean with sewage and river sediments, and red tide organisms multiply and accumulate in large quantities by using nutrients such as nitrogen, phosphorus and carbon. Urban domestic sewage is even more terrible, not only with large emissions, but also with high nitrogen and phosphorus content, which is the chief culprit of red tide. " Talking about meteorological conditions, Cheng said that meteorological conditions are important factors for the occurrence of red tide, and temperature, humidity, air pressure and seawater flow also have an impact on red tide. The development and spread of red tide are also closely related to meteorological conditions.

So what is the relationship between meteorological conditions and red tide? The staff of Taizhou meteorological department made a careful analysis, because the main source of nutrients of red tide is organic matter discharged from the mainland, and the decomposition of organic matter requires certain temperature conditions, and the organic matter is closely related to the change of wind direction during the discharge into the sea. The temperature in Taizhou from May to July is higher than 20℃, and the dominant wind direction is easterly, which is conducive to the decomposition and storage of nutrients in the offshore, and it is a period prone to red tides. Of course, the occurrence of red tide was also related to the meteorological factors at that time. According to the data of Hongjia Meteorological Station in Taizhou, the average temperature in April last year and April this year was 1. 1℃ and 1.3℃ higher than normal, and the precipitation was 4 1% and 5 1% lower than normal. It is speculated that the occurrence of red tide is probably related to the previous meteorological conditions, and high temperature and lack of rain may be one of the main reasons for red tide in Taizhou. Since 1980s, the meteorological conditions of several big red tides along Taizhou coast have also confirmed this point. From May 24 to 26, 1986, early to mid-May, 1990, May 2000, early to mid-May 2006 and May 2006, the four red tides were all caused by high temperature or the same meteorological factor. Across the country, red tides occur frequently in different sea areas, such as March-May and September 9- 10/0 in the South China Sea, May-July in the East China Sea and July-September in the Bohai Sea and the Yellow Sea. Obviously, the occurrence time of red tide in different sea areas is basically consistent with the seasonal variation of rain belt displacement, which is related to the seasonal variation of atmospheric circulation.

Needless to say, to do a good job in weather monitoring and forecasting is inseparable from the forecasting, prevention, monitoring and control of red tides. Nowadays, many people feel irresistible to the marine disaster of red tide, which poses a great threat to fishery culture and offshore fishing. People talk about the color change of "tide". Fishery officials believe that the pollution source of red tide comes from industrial pollution and domestic pollution, and environmental protection is the fundamental measure that human beings can control. At the same time, the cooperation between relevant departments will have a positive impact on the control of red tide.