Gaseous envelope: atmospheric structure
The atmosphere is a multilayered gaseous envelope, each level of which has unique temperature and physical characteristics.
Troposphere This is the lowest layer of the atmosphere, extending from the Earth's surface to an altitude of 10–12 km. In this zone, general and horizontal circulation of air masses takes place. The most important feature of the troposphere is the decrease in temperature with increasing altitude, since air heating depends predominantly on the heat emanating from the Earth's surface and has its limit.
Stratosphere and ozone layer Above the troposphere, in the altitude range from 16 to 50 km, lies the stratosphere. Unlike the underlying layer, the temperature here increases with altitude. This phenomenon is associated with the presence of the ozone layer, which is concentrated predominantly at altitudes of 20–25 km. The heating of the stratosphere is due to the absorption of energy from short-wave ultraviolet rays of the Sun (with a wavelength of less than 300 nm). Under the action of this hard radiation, photolysis occurs—the splitting of molecular oxygen, which leads to the formation of ozone. It is this layer that performs the crucial function of protection against harsh ultraviolet radiation.
Mesosphere and ionosphere Above the stratosphere (from 50 to 80 km) lies the mesosphere, where the temperature trend changes again—the temperature begins to drop. Finally, at altitudes of more than 80 km lies the upper layer—the ionosphere.
Solid envelope: structure of the lithosphere
The lithosphere forms the solid framework of the planet's surface. Its composition is heterogeneous and clearly divided into layers, while the structure of the continental and oceanic parts has fundamental differences.
In the classical version, the lithosphere is formed by two main layers:
- Upper layer: consists of sedimentary rocks and granite.
- Lower layer: represented by basalt rocks.
Special attention should be paid to the structure of the solid envelope beneath the ocean. The oceanic lithosphere is thinner and simpler in structure: the granitic layer is completely absent in it, so it consists exclusively of sedimentary rocks and basalt.
An integral part of the solid envelope, forming its most superficial horizon, is the pedosphere (soil). Soil is a unique bio-inert formation that arose as a result of the long-term and joint impact of climatic factors and living organisms on surface rocks.
Water envelope: composition of the hydrosphere
The hydrosphere unites all the water reserves of the planet, forming a continuous, but physically heterogeneous envelope. Depending on the location and nature of the water masses, the hydrosphere is subdivided into several major components.
- World Ocean: the basis of the hydrosphere, covering most of the planet.
- Coastal seas: transition zones closely associated with continents.
- Continental water bodies: waters located directly on land.
Continental water bodies, in turn, are represented by various forms:
- Surface flowing and standing waters (rivers, lakes, streams).
- Groundwater hidden within the thickness of rocks.
Briefly: answers to topical questions
What is the chemical composition of the gas mixture in the troposphere?
The natural composition of dry atmospheric air is a mechanical mixture of various gases, including main components and impurities.
- Nitrogen — 78.09%
- Oxygen — 20.95%
- Argon — 0.93%
- Carbon dioxide — 0.03%
The composition also includes inert gases, and in small amounts contains ozone, carbon monoxide, iodine, methane, and water vapor.
What types of groundwater are distinguished in the hydrosphere?
Depending on the occurrence conditions in underground water bodies, the following main types of water are distinguished:
- Phreatic (unconfined ground) water — accumulates on the first aquiclude layer from the Earth's surface.
- Interstratal unconfined water — located between two aquiclude layers without pressure.
- Interstratal confined artesian water — deep-seated water possessing pressure and capable of independently flowing to the surface.
What ecological groups of living organisms inhabit the pedosphere?
The soil habitat is populated by diverse representatives of flora and fauna, forming two large groups of organisms.
- Soil flora — fungi, algae, bacteria, viruses.
- Soil fauna — unicellular organisms, protozoa, nematodes, mites, fly larvae and pupae, earthworms, as well as mammals such as moles, mice, and rats.
These organisms play an important positive role in the processes of soil self-purification and increasing its fertility.
ALG: Atmosphere (air), Lithosphere (stone), Hydrosphere (water). The three main letters of the Earth's geospheres.
Class and exam questions
What is the main difference between the continental lithosphere and the oceanic lithosphere?
In the lithosphere beneath the World Ocean, the granitic layer is absent. It consists of only two layers: an upper sedimentary layer and a lower basaltic layer.
How is the pedosphere formed?
The pedosphere, or soil, is formed on the surface of the lithosphere under the combined impact of climate and the vital activity of various living organisms on rocks.
What else to study on this topic
- Mechanisms of molecular oxygen photolysis under the action of UV radiation
- Features of general and horizontal air circulation in the troposphere
- Processes of formation of sedimentary, granitic, and basaltic rocks
- Biogenic and climatic factors of soil formation (pedogenesis)
- Interrelation of continental water bodies and groundwater
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