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: 5 Search : lambert
lambert
  لامبرت   
lambert

Fr.: lambert   

A centimeter-gram-second (cgs) unit of luminance (or brightness) equal to 1/π candle per square centimeter. Physically, the lambert is the luminance of a perfectly diffusing white surface receiving an illuminance of 1 lumen per square centimeter.

Johann Heinrich Lambert (1728-1777), German scientist and mathematician; → law.

Lambert's cosine law
  قانون ِ کوسینوس ِ لامبرت   
qânun-e cosinus-e Lambert

Fr.: loi en cosinus de Lambert   

The intensity of the light emanating in any given direction from a perfectly diffusing surface is proportional to the cosine of the angle between the direction and the normal to the surface. Also called → Lambert's law.

lambert; → cosine; → law.

Lambert's law
  قانون ِ لامبرت   
qânun-e Lambert

Fr.: loi de Lambert   

Same as → Lambert's cosine law.

lambert; → law.

Lambertian disk
  گرده‌ی ِ لامبرتی، دیسک ِ ~   
gerde-ye Lamberti, disk-e ~

Fr.: disque lambertien   

A → planetary or → satellite disk with → Lambertian surface. Such a disk has the same → surface brightness at all angles.

lambert; → disk.

Lambertian surface
  رویه‌ی ِ لامبرتی   
ruye-ye Lamberti

Fr.: surface lambertienne   

A surface whose → luminous intensity obeys → Lambert's cosine law. Such a source has a → reflectance that is uniform across its surface and uniformly emits in all directions from all its points. It appears equally bright from all viewing directions. Lambertian surface is a very useful concept for the approximation of radiant power transfer.

lambert; → surface.