Some physics of the atmosphere

The atmosphere is the densest part of the gaseous covering that envelops our planet. Due to its weight and to the property that gases have of being compressible, the whole atmosphere is in a state of hydrostatic equilibrium: this determines a horizontal stratification, in concentric ‘strata’, of the surfaces having not only a constant pressure (isobaric surfaces) and density, but also other magnitudes such as temperature, humidity or degree of ionization. The layers which are of greater interest to meteorology are the troposphere and the tropopause. Together they reach a width of about 26 km: it is here that all meteorological phenomena take place.
The main atmospheric parameters that must be known to study meteorological events are the amount of thermal energy that reaches the Earth (the temperature of the ground and of the air), atmospheric pressure and the humidity contained in the air.

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