There are two concepts of warming layer, as follows:
① For the atmosphere, the thermosphere refers to the area where the temperature rises again above the mesopause.
② According to the source and temperature distribution of geothermal energy below the surface, the crust can be divided intoThermocline、Thermostatic layerandWarming layer。The warming layer, also known as the inner tropical zone, refers to the zone below the earth's surface that is completely controlled by the earth's internal thermal activity, and the temperature increases with the increase of depth.
There are two concepts of warming layer, as follows:
① For the atmosphere, the thermosphere refers to the area where the temperature rises again above the top of the mesosphere.[1]
② According to the source and temperature distribution of geothermal energy below the surface, the crust can be divided intoThermocline、Thermostatic layerAnd warming layer.The warming layer, also known as the inner tropical zone, refers to the zone below the earth's surface that is completely controlled by the earth's internal thermal activity, and the temperature increases with the increase of depth.Generally speaking, the temperature increases steadily towards the center of the earth.Generally, the temperature increases by 3 ℃ every 100 meters.However, after reaching a certain depth, the rate of warming slowed down.[2]
Atmospheric warming layer
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In the warming layer Ntwo、OtwoO Solar radiation with very short absorption wavelength (<0.1μm) Because the air is thin, the air molecules are prone to photoionization, which makes the free electrons in the air rich, so it is also calledthe ionosphere。
As the air is thin, the temperature becomes very high (up to thousands of degrees) as long as it absorbs a little energy. The temperature change here is closely related to the activity of sunspots. When the sun is calm, this layer can extend to a height of 400 km, and during the solar activity, it can even reach 500 km up and down. Because electric ions can absorb and reflect telecommunications,Therefore, the ionosphere is greatly affected by the status of sunspot activities. When sunspot activities are intense and frequent, long-range communication and radar operations on the earth are seriously affected.that is becauseOxygen atomStrong absorption wavelength is less than 0.175μThe reason of the temperature rise caused by the solar shortwave radiation of m.At this time, the temperature will rise rapidly due to the height, sometimes up to 2000 ℃.The upper part of the warming layer is the outer gas layer from 500 to 1000 km above the ground, where the atmosphere will be bordered by outer space.Although a few air particles can even reach a high temperature of 2500 ℃, they will not feel warm, and ordinary thermometers can only measure below 0 ℃.This is because the distance between molecules is too far.
Reach an altitude of 85 kilometers above the surface. At this altitude, the remaining atmospheric gas will be stratified according to the molecular weight.The air in the warming layer is extremely thin, and the mass of this layer only accounts for 0.5% of the total atmospheric mass.At a height of more than 120km, the air density is too small to transmit sound waves. At a height of 270km, the air density is about one tenth of that of the ground air. At a height of 300km, the air density is only one tenth of that of the ground. The air is even thinner upward.
The warming atmospheric molecules absorb the shortwave radiation of the sun and the magnetic field, and their electronic energy increases, and some of them are ionized.These ionized ions and electrons formthe ionosphere。The ionosphere is divided into three layers: layer E (90~160 km), layer F1 (180~200 km), and layer F2 (more than 250 km).Due to seasonal changes, sudden layer E (Es layer, about 100 km) will appear.The ionosphere can reflect radio waves, so it is used by humans for long-distance radio communication.The electrons accelerated by the magnetic field in the high latitude region will flow in, collide with the atmospheric molecules in the thermosphere, and then be excitedionization。When those molecules return to their original state, they will emit light, which is calledaurora。[1]
Crustal warming layer
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There are many hypotheses about the source of geothermal energy in the earth's interior. It is generally recognized that the radioactive elements in the earth's interior are transformed and released heat andMantle thermal convectionCommunication;The second is the transformation of the earth's rotational energyHeat of chemical reactionHeat of crystallization and heat of gravity differentiation.In addition, the ground temperature is relatively high in the volcanic activity zone, and its heat source mainly comes from magma related to volcanic activity.[3]
The warming layer isNormal temperature layerBelow the earth's interior, the heat mainly comes from the transformation of radioactive elements inside the earth.The temperature of the earth gradually increases with the increase of depth, which can be expressed in two ways:
Geothermal gradient refers to the change rate of temperature with depth.The average geothermal gradient of the earth is 3 ℃/m, the average geothermal gradient of the seabed is 4~8 ℃/m, and the average geothermal gradient of the continent is 0.9~5.2 ℃/m.The geothermal gradient varies greatly in different regions of the worldGeothermal gradientThe largest in the United StatesOregonThe geothermal gradient is 150 ℃/km, and the smallest one is in South Africa. The geothermal gradient is only 6 ℃/km, and the geothermal gradient value in most regions varies between 20 and 50 ℃/km.
Geothermal depth orGeothermal heating gradeRefers toNormal temperature layerBelow, the depth required for each 1 ℃ increase in temperature.Geothermal gradientAnd geothermal depth are reciprocal.If the geothermal gradient of a place is 5 ℃/100m, the geothermal depth is 20m/℃.But geothermal gradient is only suitable for shallow crust, not for deep crust.If the temperature is increased by 2.5 ℃ for 100m, the geocenter can reach 160000 ℃.Therefore, some people think that the earth's core is hollow (gaseous or liquid), which is similar toseismic waveThe fact that shear waves can pass through the main part of the earth's interior is inconsistent.
Comparatively recognized calculation results:Moho surfaceThe ground temperature nearby is 400~900 ℃;lithosphereThe temperature near the bottom is about 1100 ℃;mantleThe internal temperature range is 1000~3500 ℃;earth 's coreThe internal temperature is 4000~6000 ℃.[4]
Geothermal energyIt has a great impact on coal mine production, especially when the mining work enters a deeper level, the geothermal problem should be fully considered.The main reason is that the underground temperature is too high, which will directly affect the health of front-line workers, and affect production efficiency and safety production.Therefore, in 2007, our country issued the surrounding standard Code for Design of Underground Thermal Hazard Prevention in Coal Mines (GB50418-2007), which has been implemented since December 1, 2007.
Some mines in China mainly adopt ice and water cooling systems to increase the air supply volume, increase the roadway section, increase the maintenance of the ventilation roadway, reduce the ventilation resistance, ensure adequate air volume and other measures to reduce the temperature of the working face.althoughGeothermal energyIt is harmful to mine production, but it is also a cheap resource that can be used.The development and utilization of geothermal energy have been paid more and more attention by relevant departments.[5]
Continental geothermal resources are unevenly distributed. The Mesozoic fold belt (equivalent to the circum Pacific belt) and the Cenozoic Himalayan fold belt (equivalent to the Mediterranean Himalayan belt) are two famous geotropics, as well as world-famous seismic and volcanic activity belts.Geothermal flow value orGeothermal gradientLocal scale above averageGeothermal anomaly area, there are often hot springs, hot springs, boiling springs or jet holes, sometimes formingHot water lake。All these can be directly or indirectly used by people.[6]
