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Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and ...
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.
An underwater ecosystem can have high water clarity yet low water quality, and vice versa. Scientists have observed that many lakes are becoming less clear while also recovering from acid rain . This phenomenon has been seen in the northeastern United States and northern Europe.
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.
The vertebrate eye is usually either optimised for underwater vision or air vision, as is the case in the human eye. The visual acuity of the air-optimised eye is severely adversely affected by the difference in refractive index between air and water when immersed in direct contact. provision of an airspace between the cornea and the water can ...
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.
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]
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]