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At sea level, the Rayleigh atmosphere has an extinction coefficient of approximately 13.2 × 10 −6 m −1 at a wavelength of 520 nm. This means that in the cleanest possible atmosphere, visibility is limited to about 296 km. Visibility perception depends on several physical and visual factors.
For an observer standing on a hill or tower 100 metres (330 ft) above sea level, the horizon is at a distance of 36 kilometres (22 mi). For an observer standing on the roof of the Burj Khalifa, 828 metres (2,717 ft) from ground, and about 834 metres (2,736 ft) above sea level, the horizon is at a distance of 103 kilometres (64 mi).
The standard measurement for underwater visibility is the distance at which a Secchi disc can be seen. The range of underwater vision is usually limited by turbidity. In very clear water visibility may extend as far as about 80m, [18] and a record Secchi depth of 79 m has been reported from a coastal polynya of the Eastern Weddell Sea ...
The radar horizon is a critical area of performance for aircraft detection systems, defined by the distance at which the radar beam rises enough above the Earth's surface to make detection of a target at the lowest level possible.
The term “water clarity” more strictly describes the amount of light that passes through water or an object’s visibility in water. The term “water quality” more broadly refers to many characteristics of water, including temperature, dissolved oxygen, the amount of nutrients, or the presence of algal blooms. How clear the water appears ...
7 Sea level pressure and height of pressure surface. 8 Pressure tendency. 9 Past weather. 10 See also. 11 References. ... The visibility itself is shown as a number, ...
Standard sea-level conditions (SSL), [1] also known as sea-level standard (SLS), defines a set of atmospheric conditions for physical calculations.The term "standard sea level" is used to indicate that values of properties are to be taken to be the same as those standard at sea level, and is done to define values for use in general calculations.
At visible wavelengths, varies from 20 cm at the best locations to 5 cm at typical sea-level sites. In reality, the pattern of blobs (speckles) in the images changes very rapidly, so that long-exposure photographs would just show a single large blurred blob in the center for each telescope diameter. The diameter (FWHM) of the large blurred blob ...