An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 14 Search : atmospheric
atmospheric
  جوی، هواسپهری   
javvi, havâsepehri (#)

Fr.: atmosphérique   

Pertaining to or existing in the atmosphere of an astronomical object such as a planet, moon, or star.

atmosphere; → -ic.

atmospheric absorption
  درشم ِ جوی   
daršam-e javvi

Fr.: absorption atmosphérique   

The absorption of → electromagnetic radiation in the → atmosphere mainly by → water vapor, → carbon dioxide, and oxygen. The atmosphere introduces two more limiting factors in → remote sensing: → atmospheric scattering and → atmospheric turbulence.

atmospheric; → absorption.

atmospheric circulation
  پرهونش ِ هواسپهری   
parhuneš-e havâsepehri

Fr.: circulation atmosphérique   

The large-scale movements of air around areas of high and low pressure whereby heat is distributed on the surface of the Earth. Atmospheric motion is driven by uneven heating of the planet. The atmosphere (and ocean) → transfers the excess heat from → tropics to → poles. The flow is determined by balance between → pressure gradients and the → Coriolis effect.

atmospheric; → circulation.

atmospheric dispersion
  پاشش ِ جوی   
pâšeš-e javvi

Fr.: dispersion atmosphérique   

The splitting of starlight into a spectrum in the atmosphere because the atmosphere acts as a refracting prism. This phenomenon brings about a practical problem for spectroscopic observations using a slit. → differential refraction; → atmospheric refraction.

atmospheric; → dispersion.

atmospheric emission
  گسیل ِ جوی   
gosil-e javvi

Fr.: émission atmosphérique   

The emission of electromagnetic radiation from the atmosphere due to thermal and → non-thermal processes. → Thermal emission comes mainly from → water vapor. Non-thermal processes result in emission lines oxygen (optical) and OH (near-IR). Atmospheric emission is a very significant source of noise in astronomical observations. See also → airglow, → aurora.

atmospheric; → emission.

atmospheric extinction
  خاموشی ِ جوی   
xâmuši-ye javvi

Fr.: extinction atmosphérique   

The decrease in the intensity of light from a celestial body due to absorption and scattering by Earth's atmosphere. It increases from the zenith to the horizon and affects short wavelengths more than long wavelengths, so that objects near the horizon appear redder than they do at the zenith.

atmospheric; → extinction.

atmospheric muon
  موءون ِ جوی، ~ هواسپهری   
muon-e javvi, ~ havâsepehri

Fr.: muon atmosphérique   

A → subatomic particle produced when → primary cosmic rays, impinge on the Earth's atmosphere producing a particle cascade, in which secondary particles decay into → muons. In the energy range up to 100 → GeV atmospheric muons come mostly from the decay of secondary → pions: π±→ μ± + anti-νμ. At higher energies, the → kaon contribution to the muon flux become significant, reaching the asymptotic value of 27% at about 10 TeV: K±→ μ± + anti-νμ.

atmospheric; → muon.

atmospheric neutrino
  نوترینو‌ی ِ جوی   
notrino-ye javvi

Fr.: neutrino atmosphérique   

A neutrino produced in the collision of → cosmic rays (typically → protons) with nuclei in the → upper atmosphere. This creates a shower of → hadrons, mostly → pions. The pions decay to a → muon and a muon neutrino. The muons decay to an → electron, another muon neutrino, and an electron neutrino.

atmospheric; → neutrino.

atmospheric noise
  نوفه‌ی ِ جوی   
nufe-ye javvi

Fr.: bruit atmosphérique   

Noise in radio wavelengths caused by natural atmospheric processes, mainly lightening discharges in thunderstorms. They can affect radio observations.

atmospheric; → noise.

atmospheric refraction
  شکست ِ جوی   
šekast-e javvi

Fr.: réfraction atmosphérique   

The shift in apparent direction of a celestial object caused by the bending of light while passing through the Earth's atmosphere. Since the density of the atmosphere decreases with altitude, the starlight will bend more as it continues down through the atmosphere. As a result, a star will appear higher in the sky than its true direction.

atmospheric; → refraction.

atmospheric scattering
  پراکنش ِ جوی   
parâkaneš-e javvi

Fr.: diffusion atmosphérique   

The → scattering of → electromagnetic radiation by various particles in the Earth's → atmosphere. The phenomenon is caused by collisions between photons and several scattering agents such as atoms, molecules, → aerosols, and water droplets in clouds. → Rayleigh scattering.

atmospheric; → scattering.

atmospheric turbulence
  آشوبناکی ِ جوی   
âšubnâki-ye javvi

Fr.: turbulence atmosphérique   

Random fluctuations of the atmosphere caused by the constant injection of energy into the atmosphere from solar and local sources, changing the temperature and pressure of the air where it is absorbed and leading to fluid instabilities. The development over time of the instabilities gives rise to fluctuations in the density of air, and therefore the → refractive index of the atmosphere. → turbulence; → seeing.

atmospheric; → turbulence.

atmospheric windows
  روزنه‌های ِ جوی   
rowzanehâ-ye javvi (#)

Fr.: fenêtres atmosphériques   

Gaps in → atmospheric absorption, allowing a range of electromagnetic wavelengths to pass through the atmosphere and reach the Earth.

atmospheric; → window.

Imaging Atmospheric Cherenkov Technique (IACT)
  تشنیک ِ تصویرگری ِ چرنکوف ِ جوی   
tašnik-e tasvirgiri-ye Čerenkov-e javvi

Fr.: téchnique d'imagerie Čerenkov atmosphérique   

The method used to detect very brief flashes of → Cherenkov radiation generated by the → cascade shower of → relativistic charged particles produced when a very high-energy → gamma ray (in the range 50 GeV to 50 TeV) strikes the atmosphere at a typical altitude of 10 km. Owing to this technique, it possible to discriminate cosmic gamma rays from the cosmic ray background and to determine their energy and source direction. More specifically, the incoming gamma-ray photon undergoes → pair production in the vicinity of the nucleus of an atmospheric molecule. The electron-positron pairs produced are of extremely high energy and immediately radiate in a → bremsstrahlung process. This radiation is itself extremely energetic, with many of the photons undergoing further pair production. A cascade of charged particles ensues which, due to its extreme energy, produces a flash of Cherenkov radiation lasting between 5 and 20 nano-seconds. The total area on the ground illuminated by this flash corresponds to many hundreds of square meters, which is why the effective area of IACT telescopes should be large.

imaging; → atmospheric; → Cherenkov; → technique.