1. atmosphere
(1) atmosphere
The atmosphere is the outermost layer of the earth, located between interstellar space and the ground, and is composed of various gases around the solid earth. According to the survey, there is also a small amount of air in the soil below the ground and rocks with a certain depth (generally less than 3km).
The main components of the atmosphere are nitrogen, oxygen, argon, carbon dioxide and water vapor, which account for more than 99% of the air volume, and the content of other gases is very small. In addition, the atmosphere contains a small amount of dust particles.
The total atmospheric mass is 5.6× 102 1g, which is mainly concentrated in the range below 100 km, and more than half of it is concentrated in the space below 100km. Due to the influence of gravity, with the increase of height, the density and pressure of the atmosphere tend to become thinner and lower.
The temperature and density of the atmosphere change with the height, so it has the phenomenon of stratification along the vertical ground direction. According to the regulations of the International Meteorological Organization, it can be divided into troposphere, stratosphere, mesosphere (mesosphere), ionosphere (warm layer) and diffusion layer (escape layer) from bottom to top (figure 1- 16), in which troposphere and stratosphere have great influence on the ground.
Figure 1- 16 Schematic Diagram of the Earth's Atmospheric Structure
Troposphere Troposphere is the bottom layer of the atmosphere, which is most affected by the ground and has obvious convection phenomenon. The flow of the atmosphere is called wind, and wind is an important geological force. At different altitudes and latitudes, the thickness, temperature, pressure and density of the atmosphere are different, thus forming air convection, which is an important reason for the formation of various meteorological processes such as wind, rain, snow and clouds.
The stratosphere is the atmosphere from the tropopause to a height of 35 ~ 35 ~ 55 kilometers. The stratosphere is thinner at the equator than at the poles. The airflow movement is mainly in the horizontal direction. The temperature is not affected by the ground thermal radiation, and there is a layer with more ozone (O3) in the height range of 30 ~ 55km. Ozone has the ability to absorb ultraviolet rays, and it is an important protective layer for the earth's life from solar radiation. There are few climate phenomena in the stratosphere.
(2) Climatic zone
Climatic factors are closely related to the distribution of global pressure zones, and climatic zones with similar climatic factors have obvious characteristics of latitude distribution. Due to different climatic factors, the schemes for dividing climatic zones are also different. In geological research, precipitation, temperature and humidity are commonly used to divide the global climate into humid climate zone, arid climate zone, semi-arid climate zone and cold (frozen) climate zone. The distribution and characteristics of each climatic zone are listed in table 1-3.
Table 1-3 distribution and main characteristics of climatic zones
① The humid climate zone has abundant rainfall, developed surface water, numerous lakes, abundant groundwater, lush vegetation and various biological species, and the southeast provinces of China belong to such areas. (2) The evaporation in arid climate regions often exceeds the rainfall, and the rainfall is less, which is mostly temporary running water formed in rainy season, while lakes form salty lakes with high salt content because of their large evaporation. (3) The arid climate zone is characterized by strong wind and sparse vegetation, which often forms an arid desert. Northwest China is an arid climate zone. ④ The temperature in the cold (frozen) climate zone is low, and the precipitation is mainly snow, which is often occupied by glaciers. Mainly distributed in polar regions, but also in some high mountain areas, such as glaciers on the Qinghai-Tibet Plateau in China.
Due to continental movement, land-sea change and pole displacement caused by tectonic movement, different climates can appear in the same area in different geological historical periods. Today's hot tropical climate area may also be a cold area covered with snow and ice in geological history, which can be proved by the characteristics of sedimentary rocks and biological fossils on the crust. According to the research results of Wei Gena and Ke Ben, the polar region before 280Ma was near the Hawaiian Island. At that time, Western Europe and North America were located in the equatorial belt, which was rainy and densely forested. By 230 years ago, Western Europe and North America were already located in arid climate zones. On the contrary, today's snowy Antarctic continent was a continent located in the equatorial zone 2.8 million years ago.
2. Hydrosphere and water cycle
The hydrosphere is composed of continuous water bodies on the earth's surface. The water bodies that make up the hydrosphere include oceans, rivers, lakes, swamps and groundwater. The existence of hydrosphere is one of the main differences between the earth and other planets in the solar system. It is estimated that the mass of hydrosphere is1.5×10/8t, accounting for only 0.024% of the mass of the earth, but its volume is relatively large, reaching 1.4× 109km3. Nearly 97% of the water is concentrated in the ocean, followed by polar ice sheets and glaciers on mountains, accounting for about 1.9% of the total water, and the rest is groundwater and various water bodies such as rivers, lakes and swamps distributed on land (Table 1-4).
Table 1-4 Estimation of various types of water on the earth
The water on the earth has been moving under the action of solar radiation and gravity. Water vapor in the atmosphere will condense into clouds at a certain height, and some clouds will be gathered by the wind and land on the mainland in the form of rain, snow and hail. About 60% ~ 80% of water will return to the atmosphere in the form of evaporation and leaf transpiration, and the rest will seep into the ground (groundwater) or form various surface water bodies (rivers, glaciers, etc.). ), and most of them will flow back to the ocean. Seawater will be partially evaporated by solar radiation, forming water vapor and entering the atmosphere, thus forming a huge hydrosphere cycle (Figure 1- 17).
Figure 1- 17 Hydrosphere Circulation
In the process of continuous circulation, hydrosphere purifies the environment, regulates the climate, breeds life, promotes the migration of surface materials and the energy conversion of all circles of the earth. It is of great significance both in the past and now.
3. Biosphere
Biosphere is a continuous circle composed of living things and the zones where their life activities take place. Due to the existence of atmosphere, hydrosphere and weathering layer on the earth's surface, a natural environment suitable for living things has been formed under the suitable temperature conditions on the earth. The earth is the only livable place in the universe, and creatures mainly live and distribute in the surface and water layer. However, in the soil and rock cracks below the surface (general depth < 100 m), signs of biological existence have been found in some deep-sea seabed (general depth < 4000 m) and atmosphere (within 7 ~ 8 km height).
According to statistics, there are about 500 million ~ 654.38+0 billion species of living things in geological history. However, during the long evolution of the earth, most of them have become extinct. There are about 165438+ ten thousand species of animals, about 400 thousand species of plants and at least 65438+ ten thousand species of microorganisms. The total amount of creatures and organisms in the biosphere is about11012t, which is l/ 105 of the total mass of the earth's crust. Although the biomass is small, it plays an important role in the geological process of crustal evolution. For example, the metabolism of organisms can enrich some scattered elements or components, which can be deposited to form various useful minerals under appropriate conditions, such as iron, phosphorus, coal, oil and so on. Organisms can also weather and destroy rocks, which is one of the important driving forces to change the appearance of the surface.