استقرار الجو

Schematic diagram illustrating how optical wavefronts from a distant star may be perturbed by a turbulent layer in the atmosphere. The vertical scale of the wavefronts plotted is highly exaggerated.

استقرار الجو Astronomical seeing هو حالة ثبات الغلاف الجوي واستقراره فحين يكون الغلاف الغازى الجوي غير مستقر تبدو النجوم متلألئة وتقفز الصورة حول التليسكوب ويطلق الفلكيون على هذة الحالة (الاستقرار الجوي الردئ). وحين يكون الغلاف الغازى الجوي ثابتا ومستقرا تكون الصورة صافية واضحة المعالم ويطلق الفلكيون على هذة الحالة (الاستقرار الجوى الجيد).

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التدابير الفلكية

Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 2r₀. Diffraction makes the image appear blurred. The atmosphere would make the blob move around very rapidly, so that in a long-exposure photograph it would appear more blurred.

Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 7r₀, on the same angular scale as the 2r₀ image above. The atmosphere makes the image break up into several blobs (speckles). The speckles move around very rapidly, so that in a long-exposure photograph the star would appear as a single blurred blob.

Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 20r₀. The atmosphere makes the image break up into several blobs (speckles). The speckles move around very rapidly, so that in a long-exposure photograph the star would appear as a single blurred blob.

أنظر ايضا

Transient lunar phenomenon
Mirage
Clear Sky Clock which include a weather forecast of astronomical seeing.

المصادر

مؤمن, عبد الأمير (2006). قاموس دار العلم الفلكي. بيروت، لبنان: دار العلم للملايين. {{cite book}}: Cite has empty unknown parameter: |طبعة أولى coauthors= (help)

Much of the above text is taken (with permission) from Lucky Exposures: Diffraction limited astronomical imaging through the atmosphere, by Robert Nigel Tubbs

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KOLMOGOROV, A. N. (1941). "The local structure of turbulence in incompressible viscous fluid for very large Reynold's numbers". Comptes rendus (Doklady) de l'Académie des Sciences de l'U.R.S.S. 30: 301–305.
NIGHTINGALE, N. S. (1991). "Interferometric seeing measurements at the La Palma Observatory". Monthly Notices of the Royal Astronomical Society. 251: 155–166. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
NOLL, R. J. (1976). "Zernike polynomials and atmospheric turbulence". Optical Society of America Journal. 66: 207–211. doi:10.1364/JOSA.66.000207. {{cite journal}}: Unknown parameter |month= ignored (help)
O'BYRNE, J. W. (1988). "Seeing measurements using a shearing interferometer". Publications of the Astronomical Society of the Pacific. 100: 1169–1177. doi:10.1086/132285. {{cite journal}}: Unknown parameter |month= ignored (help)
TATARSKI, V. I. (1961). Wave Propagation in a Turbulent Medium. McGraw-Hill Books.

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