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Scintillation or twinkling are generic terms for rapid variations in apparent brightness or color of a distant luminous object viewed through the atmosphere. Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ...
If the object lies outside the earth's atmosphere, as in the case of stars and planets, the phenomenon is termed astronomical scintillation; if the luminous source lies within the atmosphere, the phenomenon is termed terrestrial scintillation.
As one of the three principal factors governing astronomical seeing, scintillation is defined as variations in luminance only, and so twinkling does not cause blurring of astronomical images. It is clearly established that almost all scintillation effects are caused by anomalous refraction caused by small-scale fluctuations in air density usually related to temperature gradients. Normal wind motion transporting such fluctuations across the observer's line of sight produces the irregular changes in intensity characteristic of scintillation. The primary cause of such small scale fluctuations is turbulent mixing of air with different temperatures. Schematic diagram illustrating how optical wavefronts from a distant star may be perturbed by a turbulent layer in the atmosphere. ...
The word luminance, a synonym for luminosity, means emitting or reflecting light. ...
The soda straw appears to be broken, due to refraction of light rays as they emerge into the air. ...
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by semi-random, stochastic property changes. ...
Scintillation effects are always much more pronounced near the horizon than near the zenith (straight up). Parcels of the order of only centimeters to decimeters are believed to produce most of the scintillatory irregularities in the atmosphere. Atmospheric scintillation is measured quantitatively using a scintillometer. The zenith is the point in the sky which appears directly above the observer. ...
A Scintillometer is a scientific device used to measure atmospheric optical disturbances called scintillations, which are caused by fluctuations of the refractive index of air. ...
Scintillation effects are reduced by using a larger receiver aperture, this effect is known as aperture averaging.
Twinkling is the subject of the song Twinkle, Twinkle, Little Star (1761). A song is a relatively short musical composition for the human voice (possibly accompanied by other musical instruments), which features words (lyrics). ...
Twinkle, Twinkle, Little Star is one of the most popular English nursery rhymes. ...
1761 was a common year starting on Thursday (see link for calendar). ...
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