Astrophysics (index)

Atmosphere

(Envelope)
(gas surrounding astronomical object)

An Atmosphere is basically any gas surrounding a celestial body such as a star or a planet. It is sometimes referred to as an Envelope around the body. (The term Envelope for planets often means what is around the core, common usage in discussions of Planet Formation and early life, when the term is sometimes qualified, e.g., Gaseous Envelope.)

A Stellar Atmosphere is the Photosphere and outward, i.e., the part that directly emits or modifies Electromagnetic Radiation to space.

A planet or Moon's atmosphere may be a significant part of the mass, e.g., a Gas Giant, or nearly nothing, e.g., the Moon. It is of interest in itself, as hints to the character of the body, and as a factor in Habitability and Biosignatures. Emitted EMR and Transmission Spectroscopy are hints to its makeup, and evidence of chemical mixtures that should not last, i.e., out of Chemical Equilibrium, indicates something replenishing the mixture, e.g., a reaction with the surface, or a emission from inside the planet, or life. Atmospheric Models and Climate Models (e.g., One Dimensional Climate Model, MarsWRF) are created to study and explain planetary atmospheres.

The Earth's atmosphere serves as a well-studied example of a planetary atmosphere, and for its well-understood effects on observation, i.e., Atmospheric Windows and Seeing.

Atmospheric Retention and its lack are of interest, both to explain observations of a body's atmosphere (or its lack) and to establish that an atmosphere is being replenished, if it ought to be gone. Its Temperature, the body's Gravity, and the mass of the molecules determine if some molecules reach escape velocity and are lost: for example, Hydrogen molecules are sufficiently light that the Earth's temperature assured they haven't remained. Photodissociation can break molecules into smaller units, affecting retention, as can Gravitational Separation, i.e., Chemical Differentiation, stratification of the atmosphere by molecular weight.

The phrase Bulk Atmosphere (and similar phrases, Bulk Planetary Atmosphere) refers to the entire atmosphere, e.g., when speaking of its composition, you're speaking of a breakdown of the components of the entire atmosphere.


(planets,stars,gas)
http://en.wikipedia.org/wiki/Atmosphere
http://en.wikipedia.org/wiki/Stellar_atmosphere

Referenced by:
Abiotic Oxygen
Ablation
Absorption
Absorption Line
Advection
Aerosols
Airmass
Albedo
Adaptive Mesh Refinement (AMR)
Adaptive Optics (AO)
Apparent Magnitude (m)
ATM
Atmosphere Formation
Atmospheric Model
Atmospheric Temperature Profile
Atmospheric Tide
Aurora
Autoconversion Rate
Black Widow Pulsar (B1957+20)
Baroclinicity
Biosignature
Bow Shock
Brunt-Väisälä Frequency
Carbonate System
Carbon Star
Cassini
Chemical Equilibrium (CE)
Methane (CH4)
Cherenkov Radiation
Chromosphere
Carbon Dioxide (CO2)
Cold Trap
Comet
Coriolis Force
Cherenkov Telescope Array (CTA)
Diffraction Limited
DISORT
Deformable Mirror (DM)
Dragonfly
Dynamical Instability
Earthshine
Eccentricity (e)
Exoplanet Eclipse Light Curve
Eclipse Mapping
Emission
Ethylene (C2H4)
ExoCTK
Exosphere
Extinction
Forbidden Line
Forward Model
Gas Flow
G-CLEF
General Circulation Model (GCM)
Gemini Observatory
Geosignature
Giant Planet
GJ 1132 b
GJ 1214 b
Greenhouse Effect
Molecular Hydrogen Dissociation Front (H2 Dissociation Front)
Habitability
Hadley Cell
Acetylene (C2H2)
HD 80606 b
Helium Rain
HITRAN
Homopause
Humidity
Hydrodynamic Equations
Hydrodynamic Escape
Hydrodynamics
Hydrology
Hydrostatic Equilibrium
Image Stabilization
Internal Gravity Wave
Intertropical Convergence Zone (ITCZ)
Juno
Kuiper Airborne Observatory (KAO)
Kelvin Waves
Lyman-Break Galaxy (LBG)
Liquid Planet
Lorentz Force
Lucky Imaging
Magnetometer
Mars Express
Mass Spectrometer
Mauna Kea
M Dwarf
Metallicity (Z)
Magnetohydrodynamics (MHD)
MITgcm
Mixing Ratio
MUSCLES
Occultation
One Dimensional Climate Model
Optical Depth (τ)
PAH Emissions
PanCET
Phase Curve
Photoevaporation
Planet Formation
Radiometer
Ram Pressure
Rayleigh Scattering
Red Noise
Reducing Atmosphere
Retrieval
Reynolds Number (Re)
Radiative Forcing (RF)
Rossby Number (Ro)
Rossby Waves
Radiative Transfer Code (RT Code)
Scale Height (H)
Solar Dynamics Observatory (SDO)
Spectral Energy Distribution (SED)
Seeing
Solar Constant
Stellar Atmosphere
Stellar Structure
Stellar Temperature Determination
Subgrid-Scale Physics
Sublimation
Super-Earth
Superrotating Wind
Surface Reaction
Surface Temperature
TAM
Taylor-Proudman Theorem
Thermal Wind
Three Dimensional Model
Titan
Transiting Planet
Transit Spectroscopy
Transmission Spectroscopy
Turbulence
Ultimate Spitzer Phase Curve Survey (USPCS)
Very-High-Energy Gamma Rays (VHEGR)
Vortex
Water Lines
Water Vapor Planet
Weathering
Atmospheric Window
Wide Field Infrared Explorer (WIRE)
Zonal Flow

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