Back نافذة سنيل Arabic Fenêtre de Snell French חלון סנל HE スネルの窓 Japanese Tetingkap Snell Malay Janela de Snell Portuguese Окно Снелла Russian சினெல்லின் சன்னல் Tamil Вікно Снеліуса Ukrainian Cửa sổ Snell Vietnamese
Snell's window (also called Snell's circle[1] or optical man-hole[2]) is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees.[3] This phenomenon is caused by refraction of light entering water, and is governed by Snell's Law.[4] The area outside Snell's window will either be completely dark or show a reflection of underwater objects by total internal reflection.
Underwater photographers sometimes compose photographs from below such that their subjects fall inside Snell's window, which backlights and focuses attention on the subjects.
- ^
Dave Hughes (1990). Tactics for Trout. Stackpole Books. ISBN 0-8117-2403-4.
Snell's circle.
- ^ David K. Lynch and William Livingstone (2001). Color and Light in Nature. Cambridge University Press. p. 79. ISBN 0-521-77504-3.
- ^ Martin Edge and Ian Turner (1999). The Underwater Photographer. Focal Press. ISBN 0-240-51581-1.
- ^ Robert Williams Wood (1914). Physical Optics. The Macmillan Company. p. 66.
circle-of-light water critical-angle 180.