Typhoon defense
What is a tropical cyclone?
Tropical Cyclone is a low-pressure vortex that occurs on the tropical or subtropical ocean surface, and it is a powerful and profound tropical weather system. Like a vortex moving forward in a flowing river, it spins rapidly around its center and moves forward with the surrounding atmosphere. In the tropical cyclone in the northern hemisphere, the airflow rotates counterclockwise around the center, but in the southern hemisphere, it is the opposite.
The life history of tropical cyclones can be divided into three stages: generation, maturity and extinction. Its average life span is about a week, the shortest is only 2-3 days, and the longest is about a month.
The generation and development of tropical cyclones need huge energy, so they are formed on the tropical ocean surface with high temperature, high humidity and other suitable meteorological conditions. According to statistics, tropical cyclones are generated in tropical oceans all over the world except the South Atlantic.
It is usually formed on the sea surface 3-5 latitudes away from the equator in tropical areas (such as the North and South Pacific, the North Atlantic and the Indian Ocean), and its movement is mainly affected by large-scale weather systems, and eventually dissipates at sea, or degenerates into an extratropical cyclone, or dissipates after landing. Landing tropical cyclone will bring serious property losses and casualties, which is a kind of natural disaster. However, tropical cyclones are also one of the components of atmospheric circulation, which can bring thermal energy and angular momentum of the earth’s rotation from the equatorial region to higher latitudes.
When tropical cyclones land or move northward to higher latitudes, they will soon die out because they lose the high temperature and high humidity conditions on which they depend. A large number of tropical cyclones are generated in the equatorial convergence zone, and there is a strong subtropical high on the north side of the equatorial convergence zone. The movement of tropical cyclones is mainly guided by the easterly airflow on the south side of subtropical high and moves westward. Such tropical cyclones often land from the southeast coast of China to the coast of Vietnam. Sometimes the subtropical high is located to the east. When the tropical cyclone moves to the western edge of the subtropical high, it will turn to the north or northeast direction and land in the coastal areas of Shandong, Liaoning, Korea and Japan, or even go north on the east side of Japan.
Benefits of typhoons:
In China’s coastal areas, typhoons hit us more or less in summer and autumn almost every year, and the loss of life and property is not small. As a kind of disastrous weather, it can be said that when it comes to typhoon, no one will show a good impression on it. However, everything has duality. Typhoon has brought disasters to human beings, but if there is no typhoon, human beings will suffer even more. Scientific research has found that typhoons have at least the following benefits for human beings:
First, with the rapid growth of global population and the development of industry and agriculture, the demand for fresh water is expanding day by day, and the limited fresh water resources on land are unevenly distributed, so the world water shortage has become increasingly serious. However, typhoon, a tropical storm, has brought abundant fresh water to people. Typhoon brings a lot of rain to the coast of China, the coast of the Sea of Japan, India, Southeast Asia and the southeastern United States, accounting for more than a quarter of the total precipitation in these areas, which is of great significance to improving the fresh water supply and ecological environment in these areas.
Secondly, the tropical and subtropical areas near the equator have the longest sunshine time, and the dry heat is unbearable. If there is no typhoon to disperse the heat in these areas, it will be hotter there and the surface sand shortage will be more serious. At the same time, the cold zone will be colder and the temperate zone will disappear. There will be no spring city like Kunming in China, nor Guangzhou with evergreen seasons, and the "Beidacang" and Inner Mongolia grassland will also cease to exist.
Third, the maximum speed of a typhoon can reach more than 200 kilometers per hour, and its energy is equivalent to the energy released by 400 2,000-ton hydrogen bombs when they explode. Wherever they go, they destroy everything. This huge energy can directly cause disasters to human beings, but it also keeps the earth in thermal balance and makes human beings live and work in peace and contentment.
Fourthly, during the formation and operation of typhoon with huge energy, with the help of lightning, long chains of water molecules can be broken and short-chain water molecules with activity can be formed. After inhaling these short-chain water molecules, the creatures on the earth can increase the vitality of life, thus making the earth’s ecology continue to develop.
Fifth, typhoons can also increase fishing output. Every time a typhoon blows, it turns over the river, and the nutrients at the bottom of the river and the sea are rolled up, and the bait increases, attracting fish to gather near the water surface, and the catch naturally increases.
The harm of typhoon to human beings;
Typhoon has brought plenty of rain to vast areas, and it has become a rainfall system closely related to human life and production. However, typhoon always brings all kinds of damage. It is one of the most serious natural disasters in the world because of its sudden and destructive power.
The destructive power of typhoon is mainly caused by strong wind, heavy rain and storm surge.
1. Strong wind
Typhoon is a huge energy pool, and its wind speed is above 17 m/s, even above 60 m/s. According to the measurement, when the wind reaches 12, the wind pressure per square meter on the plane perpendicular to the wind direction can reach 230 kilograms.
2. Heavy rain
Typhoon is a very strong rainfall system. When a typhoon lands, the rainstorm center can drop 100-300mm in a day, even reaching 500-800mm. The flood disaster caused by typhoon and rainstorm is the most dangerous disaster. The intensity of typhoon rainstorm is high, the frequency of flood is high, the spread range is wide, and it is fierce and destructive.
3. Storm surge
The so-called storm surge means that when the typhoon moves to land, due to the strong wind and low pressure of the typhoon, the sea water accumulates strongly in the direction of the coast, the tide level rises sharply, and the water waves are overwhelming to the coast. The storm surge of a strong typhoon can raise the coastal water level by 5-6 meters. Storm surge meets astronomical high tide level, resulting in high-frequency tide level, resulting in tidal overflow, seawall burst, washed away houses and various building facilities, flooded towns and farmland, and caused a large number of casualties and property losses. Storm surge will also cause coastal erosion and land salinization caused by seawater intrusion.
How to avoid danger when the typhoon comes?
Try not to go out.
2. If you are outside, don’t take shelter from the wind and rain near temporary buildings, billboards, iron towers and trees.
If you are driving, you should immediately drive to the underground parking lot or shelter.
If you live in a tent, you should immediately put away your tent and take shelter from the wind in a solid house.
If you are on the water (such as swimming), you should go ashore to take shelter from the wind and rain immediately.
6. If you are already in a solid house, you should carefully close the window and stick a "meter" pattern on the window glass with adhesive tape to prevent the window glass from breaking.
7. If there is a typhoon and thunder, lightning protection measures should be taken.
8. After the typhoon, it is necessary to pay attention to environmental sanitation and the safety of food and water.
Typhoon prevention at sea: how to avoid navigation in case of typhoon?
1. What about the ships at sea before the typhoon comes?
(1) Before the typhoon comes, the ship should obey the command and go to the shelter immediately.
(2) In case you can’t escape or encounter a typhoon, you should contact the relevant departments on the shore in time for rescue.
(3) When waiting for rescue, you should take the initiative to take emergency measures and take measures to leave the typhoon quickly and decisively, such as stopping (delaying navigation), bypassing (bypassing navigation) and crossing (passing quickly).
(4) The calm wind and waves shortly after the strong typhoon may be the calm when the typhoon eye passes. At this time, the owner of the berthing port must not go back to reinforce the ship in order to protect his property.
(5) When conditions permit, the ship shall be equipped with modern equipment such as beacon, radio communication machine and satellite phone.
(6) When there is no radio communication equipment, when a passing ship or plane is found, or when it is close to the land, you can use objects to send out easily-detected distress signals in time, such as piling up the words "SOS", setting off fireworks, sending out light and sound signals, shaking brightly-colored objects, etc.
2. How to avoid navigation when encountering a typhoon?
When a ship sailing at sea encounters a typhoon, in order to avoid being involved in the typhoon center or the storm area around the center, the method of avoiding navigation is generally adopted. The ship can lose no time to change its course and speed according to the dynamics and intensity of the typhoon, so as to keep a certain distance from the center of the typhoon, which is beyond the gale range of the wind level that the ship can resist.
The wind direction of the right semicircle of the typhoon is close to the moving route of the typhoon, and the wind speed of the right semicircle is greater than that of the left semicircle. Moreover, most typhoons turn to the right, which makes it easy to drag ships in the right semicircle into the center of the typhoon. Therefore, the right semicircle of typhoon is called "dangerous semicircle" and the left semicircle is called "navigable semicircle" in navigation.
When a ship encounters a typhoon at sea, it should judge its position according to the situation and dynamic forecast of the typhoon and the changes of wind force, wind direction and air pressure observed on the spot, so as to take appropriate navigation methods and stay away from the typhoon center as soon as possible.
The method of judging the position of the ship and the navigation measures to be taken are as follows:
(1) the wind direction changes clockwise, the air pressure is decreasing, and the wind is gradually increasing. At this time, the ship position is in the first half of the typhoon’s dangerous semicircle, that is, the dangerous quadrant, and it should sail at full speed against the wind on the starboard side of the bow.
(2) The wind direction changes counterclockwise, the air pressure keeps decreasing, and the wind force gradually increases. At this time, the ship is in the first half of the navigable semicircle of the typhoon, and should sail at full speed with the starboard stern exposed to the wind.
(3) the wind direction is constant, the air pressure is decreasing, and the wind is gradually increasing. At this time, the ship is on the way of typhoon, so it should sail at full speed with the starboard stern under the wind.
Residents’ typhoon prevention: what should I do when the typhoon comes?
Main points of preparation before typhoon comes.
1. Listen, watch or check the typhoon warning information online in time to understand the government’s countermeasures against Taiwan.
2. Close the doors and windows and fasten the structures that are easily blown by the wind.
3. Move from the dilapidated house to a safe place.
4. People in low-lying areas that may be flooded should be moved in time.
5. Check whether the facilities such as circuit, fire and gas are safe.
6. Kindergartens and schools should take temporary avoidance measures and suspend classes when necessary.
7. Open-air collective activities or indoor large-scale gatherings should be cancelled in time, and evacuation should be done.
8. Don’t travel to the area where the typhoon passes or swim on the beach, let alone go out to sea by boat.
How to prevent Taiwan in fishery before and after typhoon?
1. Before the typhoon comes
(1) Do a good job in the evacuation of personnel in high-risk places such as beaches, ships, downstream of reservoirs and waterlogged places.
(2) Strengthen the safety inspection of power facilities and equipment to ensure the safety of electricity use.
(3) Make preparations for fishery facilities and equipment to ensure the normal operation of machinery and equipment.
(4) Do a good job in the escape prevention of cultured products. Strengthen the inspection and consolidation of anti-escape facilities such as river crabs and soft-shelled turtles. At the same time, do a good job in emergency preparations for the collapse of dams and ponds caused by heavy rains.
(5) Do a good job in emergency preparations for floating heads of aquaculture varieties and disease outbreaks after typhoons.
2. After encountering a typhoon
(1) When a fishing boat at sea is in distress, it shall immediately send out a distress signal, and report the time, place, sea conditions, damage, rescue requirements, contact information and the cause of the accident to the fishery administrative department and the maritime agency, and take all effective measures to organize self-help.
(2) Fishing boats (including small fishing boats) going out to sea should return to Hong Kong as soon as possible or take shelter from the wind to the nearest port, and take measures to prevent fishing boats from colliding.
Agricultural prevention and remedy before and after typhoon crossing the border?
1. Precautionary measures for crops such as rice, vegetables and dry grain before disaster.
After the news of typhoon is released, make early preparations for places that may be hit by typhoon and flood disasters, and take timely measures to prevent and avoid disasters. Take the following measures for field crops:
Dredge ditches and open field drains to ensure smooth drainage and irrigation; Sufficient agricultural materials for disaster relief; Organize timely harvesting of mature field crops such as rice, corn, soybeans, melons and vegetables; Repair and strengthen production facilities such as greenhouses. Organize the field workers to evacuate in time.
2. Disposal measures after typhoon disaster
(1) Rice
Dredge ditches and open field drains to ensure smooth drainage and irrigation; Rinse the leaf mud and apply fertilizer in time; Spraying drugs in time to control pests and diseases. After the typhoon, a large number of leaves were injured, and the source of flooded rice fields increased, which was very prone to rice diseases, and rice planthoppers and leaf rollers also often occurred. According to the actual occurrence of pests and diseases, the corresponding pesticides should be selected in time.
(2) Vegetables
Ditching and drainage; If the vegetable field is flooded and the vegetables are damaged, the affected vegetables with market value should be actively harvested and listed to reduce losses; Strengthen the prevention and control of vegetable diseases.
(3) Dry grain crops
Timely drainage and intertillage, increase fertilizer, especially available nitrogen fertilizer, improve soil nutrient status and make plants grow rapidly; For lodging dry grain crops, the plants should be raised before new roots are formed, and the soil should be cultivated and fertilized at the same time, so that the new roots can be quickly planted.
(4) production of mulberry tea fruit
First, ditch drainage and clean up sludge and sundries. For the flooded garden, ditch and drain the canal, quickly eliminate the accumulated water in the garden, reduce the groundwater level and accelerate the drying of the topsoil. Seawater is poured into the orchard, and after the seawater is drained, it is washed with fresh water. Wash the mud on the branches and leaves of plants with water in time, remove the sundries hanging on the plants in time, and cut off some branches and leaves for plants that have been flooded for a long time.
Second, the trees that have been washed down by the flood should be righted as soon as possible, supported and fixed by brackets, and the exposed roots should be covered with soil. For trees with serious root damage, thin branches and cut leaves to reduce leaf evaporation. If the branches have been broken, cut them off in time.
The third is to loosen the soil at the right time. After flooding, the soil in the garden is hardened, which is easy to cause root hypoxia. When the topsoil in the garden is basically dry, loosen the soil in time.
The fourth is topdressing outside the roots. After waterlogging, the root system of the tree is damaged, and its ability to absorb fertilizer and water is weak, so it is not suitable to apply fertilizer to the root immediately. 0.1-0.2% potassium dihydrogen phosphate, 0.3% urea and foliar fertilizer can be used for topdressing outside the root. Once every five days or so, spray for 2-3 times. After the tree is restored, apply decomposed human and animal manure, cake fertilizer or urea to the soil to promote new roots.
The fifth is moderate pruning. The pruning amount is determined according to the degree of damage. In addition to re-pruning, some or all fruits should be picked from the damaged heavy trees to reduce the water evaporation of the waterlogged branches and leaves and the nutrient consumption of the trees.
Sixth, do a good job in pest control. After the typhoon, it is easy to induce various pests and diseases, and citrus is prone to acute anthracnose, canker, black spot disease, rust tick and red spider. Pear is prone to scab, pear rust and ring rot; Peach is prone to brown rot and anthracnose; Myrica rubra is prone to brown spot disease and red coat disease; Loquat is prone to spot disease, gray spot disease, angular spot disease, leaf blight and yellow caterpillar; Grapes are prone to black pox. Attention should be paid to the monitoring of the above pests and diseases, and once they occur, corresponding pesticides should be selected for timely prevention and control.
(Editor: Xu Lina)























