Earth is the only planet in our Solarthe 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 lead a close interaction among themselves, which is expressed by the exchange of energy and matter. In this article we will consider their composition, main characteristics and properties.
The outer shells of the Earth are the atmosphere, hydrosphere, lithosphere.
The Earth's gas shell is the atmosphere, at the bottom it isborders on the hydrosphere or lithosphere, and extends for 1000 km. There are three layers in it: the troposphere, which is moving; after it there is a stratosphere; behind it - the ionosphere (the upper layer).
The height of the troposphere is about 10 km, and the mass is 75%of the mass of the atmosphere. It moves the air horizontally or vertically. Above is the stratosphere, which extends for 80 km upwards. It forms layers, moving in the horizontal direction. Behind the stratosphere there is an ionosphere in which the air is continuously ionized.
The size of the hydrosphere - the water envelope of the Earth,is 71% of the total surface of the planet. The average salinity of water is 35 g / l. The oceanic surface has a density of about 1 and a temperature of 3-32 ° C. The sun's rays can penetrate not deeper than two hundred meters, and ultraviolet - at 800 m.
The habitat of living organisms is the biosphere, itmerges 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 depressions 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 rocky shell of the Earth,can vary from 35 to 100 km. It includes all continents, islands and the ocean floor. Below it is a pyrosphere, which is the fire envelope of our planet. It shows an increase in temperature of approximately 1 ° C every 33 meters inland. Probably, at great depth under the influence of enormous pressure and very high temperatures the rocks are melted and are in a state close to liquid.
The location of the central shell of the Earth - the nucleus -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 Earth's geospheric envelopes are constantly changing:fire - thickens, and hard - thickens. This process in its time provoked the appearance of hard stone blocks - the continents. And in our time the fiery sphere does not stop its influence on life on the planet. Its impact is very great. Constantly changing the outlines of the continents, the climate, the oceans, the composition of the atmosphere.
Endogenous and exogenous processes affect the continuous change of the hard surface of the Earth, which affects the biosphere of the planet.
All outer shells of the Earth have a common property -high mobility, because of which the slightest change of any of them immediately spreads to the whole of its mass. This explains why the uniformity of the composition of the shells is relative at different times, although they have undergone 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, she acquired the present state. Similarly, the composition of the Earth's water shell changed, which is proved by the comparative indicators of salt composition of closed waters and oceanic ones. The entire organic world also changed, and changes are still taking place in it.
