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Water clarity is a descriptive term for how deeply visible light penetrates through water. In addition to light penetration, the term water clarity is also often used to describe underwater visibility. Water clarity is one way that humans measure water quality, along with oxygen concentration and the presence or absence of pollutants and algal ...
The emitted light and the reflected light combine and may be considerably more visible than the original light. The most visible frequencies are also those most rapidly attenuated in water, so the effect is for greatly increased colour contrast over a short range, until the longer wavelengths are attenuated by the water.
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. [3]
The young human eye can change focus from distance (infinity) to as near as 6.5 cm from the eye. [32] [33] This dramatic change in focal power of the eye of approximately 15 dioptres (the reciprocal of focal length in metres) occurs as a consequence of a reduction in zonular tension induced by ciliary muscle contraction.
This can cause xanthopsia as well as a slight truncation of the short-wave (blue) limit of the visible spectrum. Subjects with aphakia are missing a lens, so UVA light can reach the retina and excite the visual opsins; this expands the visible range and may also lead to cyanopsia.
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The healthiest bubbly water you can drink is plain, unsweetened, sparkling water or seltzer — just H2O plus CO2 — over those with sweeteners, flavorings, or other additives, says Zumpano.
Accordingly, deeper water hyperiids, where the light against which the silhouettes must be compared is dimmer, have larger "upper-eyes", and may lose the lower portion of their eyes altogether. [40] In the giant Antarctic isopod Glyptonotus a small ventral compound eye is physically completely separated from the much larger dorsal compound eye ...