Disaster of typhoons
Typhoon storm surges occur mostly in summer and autumn when typhoons
are at their peak with the characteristics of fierce, fast, strong and
destructive, which can occur in all coastal areas affected by typhoons;
temperate storm surges occur mostly in spring and autumn, and also in summer,
generally, the process of increasing water is relatively gentle, and the height
of increasing water is lower than that of typhoon storm surges, middle latitude
coastal areas often occur, especially along the coasts of the North Sea of Europe,
the East Coast of the United States and the northern coast of China.
The Northwest Pacific Ocean is the most suitable region for typhoon generation
in the world, accounting for 36% of the total frequency of typhoon generation.
China is one of the countries most attacked by typhoons, according to the
statistics of the past 50 years, about 7 to 8 typhoons landed in China every year.
According to statistics from 1988 to 2004, the annual economic losses caused by
typhoons in the mainland of China are 23.35 billion yuan, 440 deaths, 307,000
collapsed houses and 288.5*104 hm2 affected areas of crops.
China has a large latitude span, and parts of southern China often suffer from
tropical cyclone disasters with high frequency and large losses.The frequency of
tropical cyclones in China is rare in the world.The global average annual occurrence
of tropical cyclones with maximum wind force of 8 or more near 80 centers, of
which 28, or about 35%, occur in the Northwest Pacific Ocean.On average, about 7
Tropical Cyclones Landed on the coastal areas of China every year.On August 2,
1922, a strong typhoon storm surge hit Shantou area, causing a huge storm surge
disaster, more than 70,000 people were killed and countless people were displaced,
this was a storm surge disaster with the largest number of deaths in China since
the 20th century,at that time, the intensity of typhoon exceeded 12 levels, resulting
in an increase of water up to 3.5m.In some years, Tropical Cyclones Landed continuously
in a very short period of time, which caused great difficulties in defense work.No.
0414 (Yunna)landed in Wenling, Zhejiang province on August 12, 2004,which was the
strongest typhoon landing in Zhejiang in 48 years and the strongest typhoon landing
in the mainland of China in 8 years.
Affected by typhoon "Yunna", heavy rainstorms fell in Zhejiang, Fujian, Jiangxi,
Anhui, Henan, Hubei and Hunan provinces,parts of were torrential rain or the rainstorm,
while effectively alleviating drought and increasing water storage in rivers and reservoirs,
precipitation also had a serious impact on Zhejiang and other provinces, a total of 18
million people were affected, 184 people died, 9 people were missing, and more than 700,000hm
crops were affected, the direct economic loss was more than 20 billion yuan.
The strongest tropical cyclone recorded in history was typhoon Tipper, which
occurred in the Northwest Pacific October 12,1979.The estimated sustained wind
speed at the center was 85m/s.The maximum rainfall caused by tropical cyclone
occurred from 7 to 8 January 1966, and the rainfall of tropical cyclone Dennis
was 1144 mm within 12 hours.The most deadly tropical cyclone was the Bangladesh
Cyclone in 1970, which killed at least 300,000 people.The most devastating tropical
cyclone was Hurricane Andrew in 1992, which hit the Bahamas, Florida and other places
in the United States, causing property losses of up to 26.5 billion dollars.
Benefits of typhoons
Typhoons not only bring severe disasters such as storms to landing areas, but also
have certain benefits.For some areas, if there are no typhoons, there will be no
crop growth and agricultural harvest in these areas.Typhoons can sometimes play a
beneficial role in relieving drought.In addition, typhoons play an important role
in regulating the earth's heat and maintaining the heat balance. Scientific research
has found that the benefits of typhoons to human beings are as follows:
(1) With the rapid increase of global population and the development of industry and
agriculture, the demand for freshwater is expanding day by day, in addition, the
limited freshwater resources on land are unevenly distributed, and the worldwide
water shortage has become more and more serious.Typhoon, a tropical cyclone, has
brought plenty of fresh water to people.Typhoons bring a large amount of rainwater
to the coastal areas of China, Japan, India, Southeast Asia and southeastern United
States, accounting for more than a quarter of the total precipitation in these areas,
which has a great significance to improve freshwater supply and ecological environment
in these areas.
(2) The tropical and subtropical regions near the equator have the longest sunshine
time and the most unbearable dry and hot weather, if there is no typhoon to dissipate
the heat in these areas, which will be hotter there and the sandy desert on the surface
will be more serious.Meanwhile, the cold zone will be colder and the temperate zone will
disappear. There will be no spring city like Kunming in our country, nor Guangzhou, which
is evergreen all the year round, the "Beidacang" and Inner Mongolia grassland will no
(3) The maximum speed of a typhoon can reach more than 200 km per hour, the energy is
equivalent to the energy emitted by 400 hydrogen bombs of 2000t class when they explode,
wherever they go, they have unbreakable power.This huge energy can directly cause disasters
to human beings, but it also relies on the huge energy flow to keep the earth in thermal
balance, so that human beings can live and work in peace and contentment.
(4) During the formation and operation of typhoons with enormous energy, the long chain
of water molecules can be broken by lightning and other functions, and the short chain of
water molecules with activity can be formed.After inhaling these short-chain water molecules,
the organisms on the earth can increase the vitality of life and make the earth's ecology
(5) Typhoons can also increase fishing production. Whenever a typhoon hits, which turns the
river upside down, rolls up the nutrients at the bottom of the river and sea, increases bait,
attracts fish to gather near the water surface, and naturally increases catches.
Prevention of typhoons
Strengthening the monitoring and forecasting of typhoons is an important measure
to mitigate the typhoon disaster.The detection of typhoons is mainly uses
meteorological satellites.The presence and size of typhoons can be seen clearly in
satellite images.Using meteorological satellite data, we can determine the location
of typhoon center, estimate the intensity of typhoon, monitor the direction and speed
of typhoon movement, and the areas where storms occur, which play a key role in preventing
and mitigating typhoon disasters.When the typhoon reaches the offshore, radar can also
be used to monitor the trend of the typhoon.In addition, the forecasters of the meteorological
station analyze the trend, landing place and time of typhoons according to various data
obtained, issue typhoon forecast, typhoon warning or emergency warning in time, serve the
public through TV, radio and other media, and provide decision-making basis for governments
at all levels at the same time.Publishing typhoon forecast or warning is an important
measure to mitigate typhoon disasters.
Today, with the rapid development of science and technology, modern equipment has been
able to accurately predict the specific movement direction, landing point and time of
the wind.As long as we take effective defensive measures, improve the level of scientific
detection and early warning, do well in prevention, resistance and rescue, and seek
advantages and avoid disadvantages, we can minimize the degree of disaster.
Early warning signals of typhoons
Early warning signals of typhoons are divided into four levels, which are expressed in
blue, yellow, orange and red respectively, shown in table 6-5.
Table 6-5 Early warning signals and preventive guidelines of typhoon disaster
[Preventive measures] Before typhoon arrives, it is necessary to transfer to
safety zone in time to avoid the above places which are easy to cause casualties,
never take shelter from the wind and rain.
Timely reinforcement of high-altitude objects
Strong winds can blow down high-altitude objects, which can easily cause injury
and death.Such as balconies, roof pots, air conditioning outdoor units, awnings,
solar water heaters, roof sundries, sporadic items, tools, building materials on
construction sites are easily blown down by the wind, causing casualties.
[Preventive measures]To fix pots and other items in time, construction
enterprises should arrange and stack construction equipment, tools and sporadic
materials to ensure safety.
Walking away from rivers, lakes and sea bridges
Doors, windows and curtain wall glasses are easily broken by strong wind,
causing glass splashing to kill and injure people; pedestrians are blown down
in the water or on the road, bridge and water edge, and are killed, injured or
drowned;wires are blown off by the wind, causing pedestrian casualties; ships at
sea (inland) are capsized and sink by the wind and waves, and vehicles on the
highway, especially on the highway, are blown over causing casualties.
[Preventive measures] Before typhoon comes, pedestrians should take
shelter from wind and rain in a safe place in time and avoid walking on embankments
and bridges near rivers, lakes and seas as far as possible, as long as ships
return to harbour in time to take shelter and anchor, people on board must take
shelter from wind and vehicles must avoid driving in areas affected by strong winds.
How to avoid a typhoon at sea? What about ships at sea before a typhoon arrives?
(1) Before typhoon approaching, the ship should obey the command and take
shelter in the shelter immediately.
(2)If it is too late to escape or encounter a typhoon, it is necessary to
contact the relevant departments on shore in time for rescue.
(3) When waiting for rescue, we should take the initiative to take emergency
measures and take prompt and decisive measures to leave the typhoon, such
as stopping (stagnating), deviating (going around), passing (passing thorough quickly).
(4)Soon after the strong typhoon, the wind and waves are calm, maybe when the
eye of the typhoon passes by, at this time, the owner of the 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 beacon machines,
radio communication machines, satellite telephones and other modern equipment.
(6) In the absence of radio communication equipment, when passing ships or
aircraft are found, or close to land, objects can be used to send out easily
detectable distress signals in time, such as stacking “SOS”, setting off
fireworks, sending out light and sound signals, shaking colorful objects, etc.
How to avoid a typhoon?
When a ship sailing at sea encounters a typhoon, the avoidance method is usually
adopted to avoid being involved in the storm area in the center or periphery
of the typhoon.Ships can change their course and speed according to the dynamics
and intensity of typhoon, so that they can keep a certain distance from the center
of typhoon, and be outside the range of strong wind which the ship can resist.
The wind direction of the right half circle of typhoon is close to the moving
route of typhoon, the wind speed of the right half circle is larger than that
of the left half circle, and most typhoons turn to the right, which makes it easy
to roll ships into the center of typhoon in the right half circle,therefore, the
right half circle of typhoon is called “dangerous half circle” and the left half
circle is called “navigable half circle” at sea.
When a ship encounters a typhoon at sea, it should locate itself according to the
typhoon's condition and dynamic forecast, as well as the changes of wind, 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 methods for judging the ship's
position and the navigation measures to be taken are as follows:
(1) The wind direction changes clockwise, the pressure drops continuously, and the
wind force increases gradually; at this time, the ship position is in the front half
of the dangerous semi-circle of typhoon, that is, the dangerous quadrant, and should
sail at full speed with the starboard overhead wind at the bow.
(2) The wind direction changes counter-clockwise, the pressure drops continuously,
and the wind force increases gradually, at this time, the ship position is in the front
half of the navigable semi-circle of the typhoon, and it should sail at full speed with
the starboard stern under the wind.
(3) The wind direction remains unchanged, the pressure drops continuously, and the wind
force increases gradually; at this time, the ship is on the way of typhoon, and should
sail at full speed with the starboard stern under the wind.
How to judge whether the typhoon is far away?
Does it mean that the typhoon has been far away? When the storm stops suddenly,
it may be a phenomenon that enters the eye of the typhoon, not that the typhoon
has been far away, in a short time, the storm will suddenly come again.Thereafter,
the wind and rain gradually decreased, and became intermittent rainfall, slowly,
the wind became smaller, the clouds rose, and the rain stopped,that is when the
typhoon left.If the eye of the typhoon does not pass through the local area, but
the wind direction gradually changes from a northerly wind to a southerly wind,
and the wind and rain gradually become smaller, the pressure gradually rises, the
clouds gradually dissipate, and the weather turns better, which also means that the
typhoon is moving away.