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Thermosphere, one of the layers into which the earth's atmosphere is ideally divided, in order to best describe it. Moving away from the earth's surface, towards sidereal space, we don't always find the same characteristics. Change the temperature, the composition and also the state of excitation or not of the molecules and particles. So it's good divide into zones and understand what happens and why.
Thermosphere: what it is
The thermosphere, starting from the Earth's crust and moving away, the fourth layer of the earth's atmosphere appears, the penultimate, therefore, between the mesosphere and the exosphere. We can locate it in that strip that goes from 95 km to about 500 km of altitude therefore almost fully embraces Kármán's line, located at an altitude of 100 km.
This line, ideal, is a convention, it was drawn in order to distinguish flights into two categories, those aeronautics they are within this line, those astronautics, on the outside. The Karman line, and the whole thermosphere, are also important for the fate of the meteors and solid bodies that from space approach our planet. In fact, it is precisely by crossing this ideal border that they begin to ignite and disintegrate.
It is the beginning of their end.
The ionosphere consists of the thermosphere and the outermost part of the mesosphere, the layer that precedes it. Throughout this area we find gas molecules in the ion state, a very important fact for us who live on Earth, even if very far from sea level.
Among the various practical consequences of the presence of these ionized particles, there is their contribution in the field of telecommunications: they reflect some radio transmissions towards the earth's surface, the ionospheric propagation it has often been used by radio amateurs.
As we mentioned when talking about the Karman's line, the thermosphere also acts as a "shield" for us terrestrials, partly avoiding us to be targeted by small meteorites that crumble right in this layer, arriving to us already reduced to debris.
The layers of the atmosphere were thus defined precisely observing the inversions of the vertical thermal gradient. Following the alternations of its sign starting from the troposphere, it is understood that a continuum occurs in the thermosphere increase in temperature with height.
We have to build on what emerges from the intersection between data and theoretical calculations and it seems that 110 km and 120 km, you have about 0 ° C and at 150 km you get to temperatures equal to a few hundred degrees above zero. If we reach the termopause, which divides the thermosphere from the exosphere, we can also imagine temperatures of around 1000 degrees.
Thermosphere and ionosphere
There ionosphere includes all the thermosphere and part of the layer that precedes it, is an area with very particular characteristics and to study perpetually because with many findings on the daily life of man and the Earth in general. In ionosphere radio waves are reflected and layers D, E, F1 and F2 are able to reflect long, medium, short radio waves. To learn more about the ionosphere, we refer you todedicated article.
Thermosphere: Northern Lights
In the thermosphere it "generates" that wonderful phenomenon that we often admire going north. In Northern Europe but also in Canada, Alaska and Greenland. I'm talking about the Northern Lights, but it also applies to the Southern Lights, because both polar auroras. For those unfamiliar with them, these are bright and colorful arcs that appear in the night sky in some periods and only in some areas.
This happens when the oxygen and nitrogen atoms which absorb energy from the solar wind, re-emit it in the form of electromagnetic radiation.
THE satellites are needed for TVs while they are not for radios, not for all. This happens because of the thermosphere and the ionosphere. Precisely because of the different behaviors that their particles have with radio waves and those of television broadcasts, there is this difference.
Radio broadcasts can be broadcast to multiple points on the earth's surface without the need for any satellite, television broadcasts require its presence in order to reach the various points scattered on the earth's surface
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