Earth is the only planet in our solar system on which life was born. In many respects this was facilitated by the presence of six different shells: the atmosphere, hydrosphere, biosphere, lithosphere, pyrosphere and centrosphere. All of them are closely interconnected, which is expressed by the exchange of energy and matter. In this article we will consider their composition, basic characteristics and properties.
The outer shells of the Earth are the atmosphere, hydrosphere, lithosphere.
The gas shell of the Earth is the atmosphere, below it borders on the hydrosphere or lithosphere, and upwards extends for 1000 km. Three layers stand out in it: the troposphere, which is moving; after it is the stratosphere; behind it is the ionosphere (upper layer).
The height of the troposphere is about 10 km, and the mass is 75% of the mass of the atmosphere. Air travels in it in a horizontal or vertical way. Above is the stratosphere, which extends 80 km up. It forms layers, moving in the horizontal direction. Beyond the stratosphere, there is an ionosphere in which air is constantly ionized.
The size of the hydrosphere - the water shell of the Earth, is 71% of the entire surface of the planet. The average salinity of water is 35 g / l. The ocean surface has a density of about 1 and a temperature of 3-32 ° C. The sun's rays can penetrate no deeper than two hundred meters, and ultraviolet rays - at 800 m.
The habitat of living organisms is the biosphere, it merges with the hydrosphere, atmosphere and lithosphere. The upper edge of the biosphere rises to the upper balls of the troposphere, and the lower reaches the bottom of the troughs in the oceans. It distinguishes the sphere of animals (more than a million species) and the sphere of plants (more than 500 thousand species).
The thickness of the lithosphere - the stone shell of the Earth, can vary from 35 to 100 km. It includes all the continents, islands and the ocean floor. Below it is the pyrosphere, which is the fiery shell of our planet. In it, a temperature increase of approximately 1 ° C is observed every 33 meters in depth. Probably, at great depths, under the influence of tremendous pressure and very high temperatures, the rocks are molten and are in a state close to liquid.
The location of the central shell of the Earth - the core - 1800 km in depth. Most scientists support the version that it consists of nickel and iron. In it, the temperature of the components is several thousand degrees Celsius, and the pressure is 3,000,000 atmospheres. The state of the nucleus has not yet been reliably studied, but it is known that it continues to cool.
The geospheric shells of the Earth are constantly changing: the fiery shell is thickening, and the solid shell is thickening. This process at one time provoked the appearance of stone solid blocks - continents. And in our time, the fiery sphere does not stop its influence on life on the planet. Its impact is very large. The contours of the continents, climate, oceans, and the composition of the atmosphere are constantly changing .
Endogenous and exogenous processes affect the continuous change in the Earth’s solid surface, which affects the planet’s biosphere.
All the outer shells of the Earth have a common property - high mobility, due to which the slightest change in any of them immediately spreads to its entire mass. This explains why the uniformity of the composition of the shells is relative at different times, although they underwent significant changes during geological development. For example, in the atmosphere, according to many scientists, initially there was no free oxygen, but it was saturated with carbon dioxide. And later, as a result of the vital activity of plants, it acquired its present state. The composition of the Earth’s water envelope has changed in a similar way, which is proved by comparative indicators of the salt composition of closed waters and oceanic ones. The whole organic world has also changed; changes are still taking place in it.