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Factors affecting visibility include illumination, length of the light path, particles which cause scattering, dissolved pigments which absorb specific colours, and salinity and temperature gradients which affect refractive index. [5] Visibility can be measured in any arbitrary direction, and for various colour targets, but horizontal ...
A diver enters crystal clear water in Lake Huron. 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.
Visibility, the distance at which objects can be seen in a medium, and illumination, the level of ambient natural of artificial light, are environmental factors which influence the ability of a diver to perform the goal of a dive, and can also strongly affect the safety of the dive.
The environment may affect gear configuration: for instance, freshwater is less dense than saltwater, so less added weight is needed to achieve diver neutral buoyancy in freshwater dives. [115] Water temperature, visibility and movement also affect the diver and the dive plan. [116]
The international definition of fog is a visibility of less than 1 km (3,300 ft); mist is a visibility of between 1 km (0.62 mi) and 2 km (1.2 mi) and haze from 2 km (1.2 mi) to 5 km (3.1 mi). Fog and mist are generally assumed to be composed principally of water droplets, haze and smoke can be of smaller particle size.
While ocean color is a key theme of ocean optics, optics is a broader term that also includes the development of underwater sensors using optical methods to study much more than just color, including ocean chemistry, particle size, imaging of microscopic plants and animals, and more.
An underwater environment is a environment of, and immersed in, liquid water in a natural or artificial feature (called a body of water), such as an ocean, sea, lake, pond, reservoir, river, canal, or aquifer. Some characteristics of the underwater environment are universal, but many depend on the local situation.
Several factors affect the diver, including immersion, exposure to the water, the limitations of breath-hold endurance, variations in ambient pressure, the effects of breathing gases at raised ambient pressure, effects caused by the use of breathing apparatus, and sensory impairment. All of these may affect diver performance and safety. [1]