What's the special weather in China? Don't look for geography books such as cold wave, typhoon, sandstorm and plum rain.

Volcanic eruption is the release of magma and other ejecta from the crater to the surface in a short time. Because the magma contains a large number of volatiles and the confining pressure of the overlying strata, these volatiles cannot overflow when dissolved in the magma. When the magma rises close to the surface, the pressure decreases and the volatiles are released sharply, thus forming a volcanic eruption. Volcanic eruption is a peculiar geological phenomenon, a manifestation of crustal movement and the strongest display of heat energy inside the earth on the surface.

Edit the types of volcanic eruptions in this section.

Due to the influence of magmatic properties, underground magma chamber pressure, volcanic tunnel shape, volcanic eruption environment (land or underwater) and other factors, the forms of volcanic eruption are very different, and generally there are the following categories:

Fracture eruption

Magma overflows the surface along a huge crack in the earth's crust, which is called fissure eruption. There is no strong explosion phenomenon in this eruption, and the ejecta are mostly basic molten slurry, which often forms a lava platform with a wide coverage after condensation. For example, the Permian Emei Mountain basalt distributed in the border area of Sichuan, Yunnan and Guizhou in southwest China and the Tertiary Hannuoba basalt north of Zhangjiakou in Hebei belong to fissure eruption. Modern fissure eruption is mainly distributed in the mid-ocean ridge at the bottom of the ocean. Only Iceland can see this kind of volcanic eruption on the mainland, so it is also called Icelandic volcano.

Central nozzle eruption

Underground magma is ejected from the surface through a tubular volcanic passage, which is called central eruption. This is the main form of modern volcanic activity, which can be subdivided into three types:

(1) Quiet type: When a volcano erupts, only a large amount of hot lava quietly overflows from the crater and flows slowly along the hillside, just like rice soup cooked in an electric rice cooker. Overflow is mainly alkaline molten slurry with high temperature, low viscosity and easy flow. Less gas, no explosion, Hawaii volcano is its representative, also known as Hawaiian type. People can enjoy this volcano to their heart's content.

(2) Explosive type: when the volcano erupts, it produces a violent explosion, and at the same time, it ejects a large amount of gas and pyroclastic materials, and the ejected molten slurry is mainly medium-acidic molten slurry. 19021216 In February, the eruption of Mount Pere in the West Indies shocked the whole world. It spewed out thick magma, and at the same time spewed out a lot of pumice and fiery volcanic ash. This volcanic eruption, which killed 26,000 people, falls into this category, also known as Pei Lei type.

(3) Intermediate type: it belongs to the transitional type between calm eruption and explosive eruption, and this type is dominated by intermediate-basic lava eruption. If there is an explosion, the explosive force is not great. It can erupt smoothly for months or even years and is characterized by intermittent eruption. Its representative is the stron Boulder volcano on the Lipari Islands near the Italian west coast. The volcano erupts about every 2-3 minutes, and the flame of volcanic eruption can still be seen 50 kilometers away at night, so it is known as the "Mediterranean lighthouse". Also known as Stromboli style. Some people think that Wudalianchi volcano in Heilongjiang belongs to this type.

(4) Seepage eruption

Edit the stage of this volcanic eruption.

1, gas explosion

During the gestation period of volcanic eruption, due to gas dissolution and earthquake swarm, the degree of cracks in overlying rocks increased and the pressure decreased, while the amount of gas dissolved in magma increased, the volume of magma gradually expanded, the density decreased and the internal pressure increased. When the internal pressure greatly exceeds the external pressure, the gas explodes violently in the fracture density area of overlying rock, which breaks the rock and opens the channel of volcanic eruption. First, the debris is ejected, and then the magma erupts.

2. Formation of eruption column

After the gas explosion, the gas sprayed the cuttings and deep magma in the channel into the sky with great jet force, forming a high eruption column. The eruption column can be divided into three areas:

(1) air impact zone: located at the lower part of the eruption column, equivalent to one tenth of the height of the whole eruption column. Because the gas rushes out of the crater with great speed and strength, although the density of ejected rocks and other substances far exceeds the density of the atmosphere, it will also be thrown into the sky. When the air shock wave rises in the volcanic tunnel, its speed gradually increases. When it is ejected from the earth's surface and shot into the sky, its speed gradually decreases due to the pressure of the atmosphere and the consumption of ejection energy. The matter that is washed into the sky by the air begins to fall at different heights according to its gravity.

(2) Convection zone: located in the upper part of the gas impact zone, it is called convection zone because the gas impact speed of the eruption column slows down, the gas in the gas column diffuses outward, and the gas in the atmosphere is constantly replenished, forming convection of gas inside and outside the eruption column. Dense matter in this area began to decline. Substances whose density is less than that of the atmosphere continue to rise under the action of atmospheric buoyancy. The height of the gas column in the convection area is relatively large, accounting for about seven tenths of the total height of the eruption column.

(3) Diffusion zone: located at the top of the eruption column, the pressure between the eruption column and the upper atmosphere is basically balanced. The eruption column keeps rising, and the gas and low-density substances in the column diffuse horizontally, so it is called diffusion zone. The volcanic ash brought into the sky will form a volcanic ash cloud, which can float in the air for a long time, which will have a great impact on the regional climate and even cause disasters. The column height in this area accounts for about two-tenths of the total column height.

3. The collapse of the eruption column

In the process of rising, the eruption column carries debris with different particle sizes and densities, and collapses at different heights and stages according to the gravity. There are four main factors that determine the collapse speed of the eruption column:

(1) The crater radius is large, the gas impulse is small, and the column collapses quickly;

(2) If the content of cuttings in the eruption column is high, the particle size is large and the density is high, the column will collapse quickly;

(3) If many solid rocks in the eruption column return to the air repeatedly, the column will collapse quickly;

(4) If surface water is added to the eruption column, the density of the column can be increased and the column will collapse quickly. On the contrary, if the eruption column stays in the air for a long time, it will slowly collapse.

Volcanic eruptions are inconsistent. Just like Kilauea volcano in Hawaii, lava has already quietly flowed out in advance. Because lava flows slowly, it only destroys property and does not endanger life. However, pyroclastic eruption or steam explosion (or violent steam explosion) like 1883 Krakato volcano in Indonesia caused heavy casualties.

Volatile substances play an important role in the process of volcanic eruption, which is both the product and the driving force of volcanic eruption. During the whole process from magma generation to volcanic eruption, the activities of volatile substances have played a role.

British scientists believe that the eruption of super volcano may destroy mankind.

British scientists believe that human beings may be destroyed in a super volcanic eruption. Stephen cerf of the University of Great Britain told an e-magazine reporter that there was no way to stop the disaster. At present, scientists are busy making various strategies to resist "external threats", such as how to prevent asteroids from colliding with the earth, but rarely consider that the main danger may come from the inside of the earth.

Geophysicists assert that the eruption intensity of some volcanoes is hundreds of times that of the past, and the earth experienced such a large-scale disaster not long before the emergence of civilization.

American geologists discovered the shallow volcanic ash dead layer in Yellowstone National Park earlier, believing that its formation was caused by the super volcanic eruption 620,000 years ago. Therefore, some funnel-shaped craters can still be seen here, which are all craters formed after destructive volcanic eruptions.

In the report to the British government's working group on natural disasters, the consequences of this super volcano eruption have been described in detail-a large area will be covered by lava, and dust and ash scattered into the atmosphere will prevent a lot of sunlight from reaching the earth's surface, which will undoubtedly change the global climate.

According to the research of Michael Ram Pi Nuo of new york University, 74,000 years ago, the super eruption of Sumatra volcano caused global cooling and destroyed 3/4 plants in the northern hemisphere. Some charged clouds and others with different charges, or charged clouds discharge rapidly between the earth. This rapid discharge process will produce strong lightning accompanied by loud noise. This is the lightning and thunder we see.

Of course, the discharge between clouds is mainly harmful to aircraft, and has no effect on buildings and people and livestock on the ground. Clouds emitted to the earth are very harmful to buildings, electronic and electrical equipment, and people and livestock.

There are usually three main forms of lightning strike: one is the rapid discharge between charged clouds and a point on the earth, which is called "direct lightning strike". The second is that charged clouds bring different charges to a certain area of the ground due to electrostatic induction. When direct lightning strikes, the clouds are charged and disappear quickly, and local high voltage appears in some areas of the ground due to the large stray current resistance, or the phenomenon that strong pulse current induces electromagnetic induction to surrounding wires or metal objects during the discharge of direct lightning is called "secondary lightning" or "induced lightning". The third is "spherical thunder".

Edit the power of lightning in this paragraph.

The average lightning current is about 20 000A (even larger), the lightning voltage is about10v (safe voltage 36V), the lightning time is about one thousandth of a second, and the average power emitted by lightning is 2 billion kilowatts (the power of ordinary rice cookers is lower than1000w).

The Three Gorges Hydropower Station, the world's largest hydropower station built in China, has a total installed capacity of 654.38+08.2 million kilowatts, which is only one thousandth of the lightning power.

Of course, although the electric power of lightning is very large, the electric power of lightning current is not large because of the short discharge time, which is about 5555 degrees at a time.

There are more than 100 times of lightning every second in the world, and the total electric energy released by lightning in one year is about175 billion kWh.

If the one-time electricity bill is 0.30 yuan, then the annual lightning value in the world is 5.25 trillion yuan, which is a huge wealth. However, due to the short time of lightning, human beings can't capture this kind of electricity, and there is no way to use lightning electricity in the world at present.

Edit the harm of lightning in this paragraph.

There are millions of lightning flashes in nature every year. Lightning disaster is one of the top ten serious natural disasters announced by the United Nations International Decade for Disaster Reduction. The latest statistics show that the loss caused by lightning has risen to the third place in natural disasters. There are countless casualties and property losses caused by lightning every year in the world. According to incomplete statistics, there are 3000-4000 casualties and property losses ranging from 5 billion yuan to 654.38+0 billion yuan caused by lightning strikes and their negative effects every year in China.

Lightning disaster covers almost all walks of life. With the rapid development of modern electronic technology, one of its negative effects is the reduction of lightning impact resistance. Advanced electronic equipment such as measurement, monitoring, protection, communication and computer network with large-scale integrated circuits as the core components are widely used in modern life fields such as electric power, aviation, national defense, communication, radio and television, finance, transportation, petrochemical industry and medical treatment. These electronic devices, which are composed of large CMOS integrated components, generally have the disadvantage of weak tolerance to transient overvoltage and overcurrent. Transient overvoltage will not only cause misoperation of electronic equipment, but also cause greater harm.

There are four main hazards caused by lightning strike:

(1) Direct Thunder

Charged clouds violently discharge a certain point on the earth, which is called direct lightning. Its destructive power is enormous. If it cannot be dumped into the earth quickly, it will cause serious damage or damage to the objects, buildings, facilities, people and animals in the discharge channel-fire, building damage, electronic and electrical system damage, and even endanger the lives of people and animals.

(2) Lightning wave invasion

Lightning does not discharge directly on buildings and equipment itself, but on cables laid outside buildings. Lightning wave or overvoltage on the cable propagates along the cable almost at the speed of light, invading and endangering indoor electronic equipment and automatic control system. Therefore, our electronic equipment and control system may be damaged before we hear the thunder.

(3) Induced overvoltage

Lightning strikes occur near equipment, facilities or lines, or lightning does not discharge directly to the ground, but only between clouds. Lightning releases charge and induces overvoltage on metal supports of power supply, data transmission lines and metal pipes.

When lightning strikes a building with lightning protection facilities, when the lightning wave discharges to the earth along the lightning receptor (lightning belt, lightning wire, lightning net or lightning rod) at the top of the building and the down lead, a strong transient magnetic field will be formed around the down lead, resulting in interference, data loss, misoperation or temporary paralysis of electronic equipment. In severe cases, components will be broken down, the circuit board will be burned, and the whole system will be paralyzed.

(4) Operating overvoltage inside the system

Due to the changes in the internal state of the system, such as the operation of circuit breakers, the input and removal of high-power loads, inductive loads, and the short-circuit fault of the system, the system parameters change, which leads to the transformation of electromagnetic energy in the power system, thus generating internal overvoltage, that is, operating overvoltage.

Although the amplitude of operating overvoltage is very small, the probability of occurrence is much greater than lightning induced overvoltage. Experiments show that induced overvoltage and internal operating overvoltage are both transient overvoltage (or transient overvoltage), which will eventually endanger electronic equipment in the form of electrical surge, including destroying printed circuit traces, components and insulation, shortening its premature aging life, destroying databases or misoperating software, and making some control components out of control.

(5) Ground potential counterattack

If lightning directly hits buildings or facilities with lightning protection devices, the ground potential of the grounding grid will rise by tens of thousands or hundreds of thousands of volts in a few microseconds. The extremely destructive lightning current will flow from the grounding part of various equipment to the power supply system or various network signal systems, or penetrate the earth insulation and flow to the power supply system or various network signal systems of another facility, thus reacting to the damage or destruction of electronic equipment. At the same time, in the wire loop without equipotential connection, high potential may be induced and spark discharge may occur.

The benefits of editing this lightning bolt

When lightning crosses, some oxygen in the air is excited into ozone. Thin ozone is not only tasteless, but also absorbs most cosmic rays, which protects the life on the surface of the earth from excessive ultraviolet rays. The high temperature caused by lightning can kill more than 90% of bacteria and microorganisms in the atmosphere, thus making the air more pure, fresh and pleasant.

According to statistics, there will be more than 365,438+billion lightning flashes over the earth every year, with an average of 100 times per second. Every time it discharges, its electric energy is as high as 654.38+10,000 kWh, which can't even be compared with the largest power device in the world. In addition, the atmosphere also contains 78% of free nitrogen that cannot be directly absorbed by crops. When lightning strikes, the current is as high as 654.38+ million amperes, and the molecules of gas in the air are heated to more than 30,000 degrees, which makes the inert nitrogen in the atmosphere combine with oxidation and become nitrogen dioxide. Heavy rain will dissolve nitrogen dioxide into dilute nitric acid, which will combine with other substances and become nitrogen fertilizer that can be directly absorbed by crops. It is estimated that there are 2 billion tons of nitrogen fertilizer "synthesized" by thunderstorms every year in the world. This 2 billion tons of nitrogen fertilizer falling from the sky is equivalent to the total output of 200,000 chemical fertilizer plants with an annual output of 654.38+100,000 tons!

Edit the preventive skills in this paragraph.

1, six lightning protection measures for units

(1) The unit shall regularly test the lightning protection facilities by qualified professional lightning protection testing institutions to assess whether the lightning protection facilities meet the requirements of national standards.

(2) The unit shall set up a person responsible for lightning disaster prevention, be responsible for lightning protection safety, establish various lightning protection and disaster reduction management rules and regulations, and implement regular inspection, inspection after thunderstorm and daily maintenance of lightning protection facilities.

(3) In the design and construction of lightning protection facilities, the construction unit shall comprehensively consider factors such as geology, soil, meteorology, environment, characteristics of protected objects, laws of lightning activity, and adopt safe, reliable, technologically advanced and economical design and construction.

(4) Lightning protection equipment, devices and equipment whose technology and quality meet the national standards should be adopted, and non-standard lightning protection products and devices should be avoided.

(5) When new buildings and installation equipment are added, the lightning protection system should be redesigned and built.

(6) In case of lightning disaster, report to the Municipal Lightning Protection Office in time, so as to handle it in time and avoid being struck by lightning again.

2. Ten secrets of personal lightning protection

(1) should stay indoors and close the doors and windows; People who work outdoors should hide in buildings.

(2) TV, audio and other electrical appliances with no or insufficient lightning protection measures should not be used, and faucets should not be used.

(3) Don't touch antennas, water pipes, barbed wire, metal doors and windows, external walls of buildings, and stay away from live equipment such as wires or other similar metal devices.

(4) Reduce the use of telephones and mobile phones.

(5) Don't swim or engage in other water sports. Outdoor ball games are not suitable. Leave the water and other open spaces and find a place to hide.

(6) Don't stand on the top of the mountain, the roof or other objects with high conductivity.

(7) Don't handle flammable items in open containers.

(8) Stay away from trees and masts when you can't hide in buildings with lightning protection facilities in the wild.

(9) It is not advisable to take an umbrella in an open field, and it is not advisable to carry badminton and golf clubs on your shoulders.

(10) It is not advisable to drive a motorcycle or ride a bike.

Edit the lightning first aid in this paragraph.

I. Main symptoms

Skin burn, crushing of eardrum or viscera, ventricular vibration, cardiac arrest, respiratory muscle paralysis.

Second, first aid.

1. The injured person lies flat, unbuttoning buttons, bras, belts, etc.

2. Immediately perform mouth-to-mouth resuscitation and chest compressions until the patient wakes up.

3. Manual or acupuncturing, such as Xuan Shi, Yongquan and Mingmen.

4. Send to the hospital for emergency treatment.

Three. prevent

1. Don't walk outdoors or take shelter under a big tree during a thunderstorm. Take off the metal on your body and squat down to prevent lightning. Turn off the TV and radio and unplug the antenna.

2. Stay away from electric lights, power supplies, pillars and walls when it thunders to prevent induced electricity.

You must quickly enter the room in a tall building, quickly get down on the mountain, swim in the water and get ashore quickly.

4. Close the doors and windows, household appliances and TV sets, and turn off the switch.

People who are outdoors feel that their hair is standing upright, their skin is stinging and their muscles are shaking, that is, they are in danger of being struck by lightning, so they should lie down or stay in place immediately to avoid lightning strike.

The extratropical cyclone is an elliptical air vortex that appears in the middle and high latitudes and the central pressure is lower than the surrounding area. It is one of the important weather systems that affect large-scale weather changes. The average diameter of extratropical cyclones is 1000 km, ranging from several hundred km to over 3,000 km. The cyclone moves eastward with the airflow to the west of the upper air, with a warm front before and a cold front after, and the south side of the fluctuation at the junction of the two is a warm area. The whole life cycle of extratropical cyclones from generation, development to extinction is generally 2-6 days. Sometimes 2-5 extratropical cyclones are formed one after another on the same front, advancing from west to east in turn, which is called "cyclone family". Temperate cyclones have an important influence on the weather changes in middle and high latitudes. Rainy weather, sometimes accompanied by heavy rain or strong convective weather, sometimes the maximum wind force near the ground can reach more than 10.

Some temperate cyclones denature after tropical cyclones enter high latitudes. The nature of cyclone changes from warm center to cold center.

The evolution process of extratropical cyclones can be roughly divided into primary stage, development stage, mature stage (occlusion stage) and extinction stage.

(1) Primary stage:

There used to be a stationary front on the ground, with cold air heading north and warm air heading south. Cold air moves from east to west, and warm air moves from west to east. When cold air is inserted southward under the front, warm air rises northward, and a closed isobar of 1 ~ 2 appears.

(2) development period

With the development of fluctuation, the air pressure drops further, the closed isobar increases, the cold air pushes further south, showers or snow showers appear near the cold front, and precipitation occurs before the warm front, and the precipitation area expands. With the development of cyclone, the disturbance at the lower level gradually develops to the upper level, the airflow spirals up, and the trough at the upper level gradually deepens.

(3) Occlusion period

At the peak of cyclone development, it has become a circular closed cycle from the ground to a height of 500 mbar. The cold front on the ground gradually caught up with the warm front and lifted the warm air on the ground, and the cyclone began to stop. At this time, the range of clouds and rain is the largest, the intensity is strengthened, the wind is increased, and the weather changes the most dramatically. However, because the ground has been occupied by cold air and become a cold vortex, the cyclone began to weaken.

(4) Extinction period

In the final stage of cyclone development, warm air only stays in the southeast corner of the ground, and the convergence of the whole cyclone center in the lower level is strengthened, and the ground is pressurized to become a cold vortex, and the low-pressure center begins to be filled. The closed circulation from the ground to about 500 mbar is weakened, the upward movement has disappeared, and the cyclone is weakened or even disappeared.

These stages are the life history of a single cyclone. It takes an average of 2 days from birth to extinction, and the elderly can reach 6 days. The development process of frontal cyclones in East Asia and China is generally about 3 days, the short one is about 1 day, and the long one is about 4 ~ 5 days.