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The theoretical black body visibility of pure water based on the values for the optical properties of water for light of 550 nm has been estimated at 74 m. [16] For the case of a relatively large object, sufficiently illuminated by daylight, the horizontal visibility of the object is a function of the photopic beam attenuation coefficient ...
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 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.
In a transmissometer the extinction coefficient is determined by measuring direct light transmissivity, and the extinction coefficient is then used to calculate visibility range. [ 2 ] Atmospheric extinction is a wavelength dependent phenomenon, but the most common wavelength in use for transmissometers is 550 nm , which is in the middle of the ...
These methods include making use of the different depths to which different frequencies of light penetrate the water. When water is clear and the seafloor is sufficiently reflective, depth can be estimated by measuring the amount of reflectance observed by a satellite and then modeling how far the light should penetrate in the known conditions.
A growing array of tools to measure conditions inside one of nature's most fearsome storms saw quite a workout in the 11 hurricanes, including five landfalling hurricanes, so far this hurricane ...
The disc is mounted on a pole or line and lowered slowly down in the water. The depth at which the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity. Since its invention, the disk has also been used in a modified, smaller 20 cm (8 in ...
Since they lie in oceans and lakes, they also measure water temperature, wave height, and dominant wave period. [14] Raw data is processed and can be logged on board the buoy and then transmitted via radio, cellular, or satellite communications to meteorological centers for use in weather forecasting and climate study.