Atmosphere

of the titles of this article is ambiguous. For further meanings see atmosphere (term clarifying).

The atmosphere (v. Greek ατμός, atmós „air, pressure, steam “and σφαίρα, sfära „ball “) is the gaseous covering around a heavenly body. It consists usually of one Mixture different gases, which can be held by the gravity field of the heavenly body. The atmosphere is closest at the surface and turns into flowing into large heights into the interplanetary area .

Table of contents

emergence

with the training of an atmosphere playing several factors a role, to which primarily the size of the heavenly body counts. The gravity field must ensure thereby,that the gas particles to the heavenly body, coming out usually from degassings, bind to remain and into space to evaporate not be able themselves.

According to the kinetic gas theory the gas particles move unordered and the faster, the more highly the temperature of theGas is and the easier it is. The attraction is not sufficient, in order to limit the loss of sufficiently fast particles in such a manner on a long-term basis that it comes to a positive particle balance, thus more gas particles by degassings is added, than by the overcoming thatAre lost to gravitation, then also no atmosphere can be formed.

Play apart from the size also the surface temperature of the heavenly body a role, which may not be to large. Also the kind of the gas particles the available is importantly, there toExample an atmosphere from hydrogen or helium many more heavily at the planets to bind is than one from oxygen or nitrogen. This is because of it the light gas particle at same temperature is substantially faster than heavy gas particles. Atmospheres elements howHydrogen to larger extent are contained therefore particularly with the very massive gas giants, that have a sufficient gravitation.

In the long run only a small minority of the heavenly bodies in a the position is to form an atmosphere and on a long-term basis actuallyto bind. Thus for example the moon does not possess an atmosphere as the next neighbour of the earth.

structure and gradients

structure by the example of the terrestrial atmosphere

pressure pattern

the pressure pattern of an atmosphere, in the case of the terrestrial atmosphere of the Air pressure, is certain in the lower ranges by the hydrostatic equation, which are written as follows with atmospheres thin in the comparison to the planet radius:

<math> {\ mathrm {D} p \ more over \ mathrm {D} h} = - g \ rho (h)< /math>

The measured variables are the pressure p, those Height of h, the Schwerebeschleunigung g and the density ρ. In case of constant temperature the equation reduces to the barometric elevator formula. In the outside range this description is however no longer valid, there itself the components due to the smallDensity on Keplerbahnen or the Magnetfeldlinien move and mutually hardly still affect each other.

subdivisions

more or less clearly against each other usually is not an atmosphere a homogeneous gas covering, but due to numerous internal and outside influences into severalto divide defined layers, which result particularly from the temperature dependence of chemical processes in the atmosphere and the radiation permeability dependent on the height. Essentially one can differentiate the following layers according to the temperature gradient:

  • At the planet surface those usually begins Troposphere, in which convection currents prevail. It limited by the tropopause.
  • The stratosphere lies in which the radiation dominates with the energy transfer. It limited by the stratopause.
  • In the mesosphere becomes, particularly by carbon dioxide, Energy radiated, so that in this layer a strong cooling takes place. It limited by the Mesopause.
  • In the thermosphere and ionize most molecules dissociate, whereby the temperature rises clearly.
  • The outermost layer is the exosphere,from that the predominantly atomic and/or ionized components from the gravity field of the planet to escape can. It is limited with presence of a magnetic field by the Magnetopause.

This arrangement shows only a rough organization, and not each layer is with allAtmospheres demonstrably. Thus the Venus possesses for example no stratosphere, smaller planets and moons possesses only an exosphere, z. B. the Merkur. For emergence and development of the dawn colors the vertical structure of the atmosphere is relevant. It is also possiblethe atmosphere not after the temperature gradient to arrange but on the basis of other criteria how:

occurrences of atmospheres

one compares the heavenly bodies of our solar system with one another, then the influence shows upthe factors relevant with the training of an atmosphere.

Under the planets the earth in a the position is to hold heavy elements such as argon (acre) in the atmosphere light elements/molecules such as hydrogen (H 2) or helium (He) lost it howeverin the course of their development. These light components show up for it the more clearly with the outside planets, the gas giants in such a way specified such as Jupiter, Saturn, Uranus and Neptun. Also planets of other star systems - the Exoplaneten - could also spektrografischen methods atmospheres to be proven.

Beside the planets also some larger moons have such as titanium, Ganymed, IO and Europe an atmosphere. The moon of the earth however does not show an atmosphere. It is for this with scarcely 1.2% of the earth masstoo small and shows besides on his sun-turned side temperatures of over 100 °C.

Composition of the planetary atmospheres of the Sonnenystems in percent by volume
planet pressure (hPa) H 2 He N 2 O 2 CO 2 CH 4 H 2O other remarks
Merkur 10,-15 22% 6% traces 42% traces - traces 29% sodium; 0.5% potassium only exosphere
Venus 92,000 - 12 ppmv 3.5% - 96.5% - 20 ppmv 150 ppmv Sulfur dioxide no mesosphere
earth 1,013 0.5 ppmv 5.24 ppmv 78.084% 20.946% 0.03% 2 ppmv ~0 4% 0.93% argon terrestrial atmosphere
Mars 6.36 - - 2.7% 0.13% 95.32% ~ 3 ppbv 210 ppmv 1.6% Argon
Jupiter >10 6 89.8% 10.2% - - - ~ 0.3% ~4 ppm gas giant
Saturn >10 6 96.3% 3.25% - - - ~ 0.45% - gas giant
Uranus >10 6 ~ 82% ~ 15% - - - ~ 2.3% - gas giant
Neptun >10 6 ~ 80% ~ 19% - - - ~ 1.5% - gas giant
Pluto 0-0.005 - - - - - expansion varies.

other

A frequent false posting for atmosphere is „Athmosphäre “or also „Atmosphere “.

see also

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