Importance of Humans and Flat Diving Mask

Humans and Flat diving mask
The flat diving mask window separates the eyes from the encompassing water by a layer of air that helps humans visualize clearly underwater. While wearing the mask, the objects appears 33% magnified and 25% closer.

Color Vision
Color vision is a capability to sense discrimination between completely different wavelengths of light. It additionally helps in visual perception of objects; their identity and characteristics (e.g., what fruit it is, whether it’s raw or not). Light gets attenuated by water due to color absorption. The cloudiness of the water and dissolved material additionally affects color absorption.

As shown within the figure, the light that is most absorbed by water is of red color, and light absorbed in smaller extent are violet, yellow, and green light. So, the light that is absorbed by water in smallest amount is of blue color.

Colors with wavelengths like red, orange, yellow are rapidly absorbed in water. Only the wavelengths like blue and green are mostly available for scattering in water as these lights can penetrate to any depth.

Underwater visibility is calculated in two ways which are represented as follows:

Horizontal visibility — to what distance one can see by looking straight ahead.

Vertical visibility —to what distance one can see by looking up or down.

The theoretical black body visibility of pure water is estimated at seventy-four meters. This estimation is based on the optical properties of water for a 550 nm wavelength light. In terribly clear water, visibility might extend as much as to 80 meters.

There are three important factors that influence underwater visibility:

• Light penetration

The intensity (of light) that penetrate the surface of water depends on 3 factors: overall level of light (a sunny versus a cloudy day), the roughness of the surface, and the angle at which the rays meet the water.

The position of Sun additionally affects the penetration power of light, with the best levels of light at noon. The Sun further sinks on the horizon; the angle of incidence is smaller, and the visibility is poor.

• Biological species

Decreased visibility in underwater could also be due to too much light, as large amount of light leads to plankton blooms or algae blooms and causes change in the color of water surface. Plankton bloom is due to the rapid increase in the population of microscopic plants (like algae) in sunlit layers of the ocean. This can reduce the visibility to less than 3 meters.

• Particulates

Particulates like suspended sand and silt carried by running water affects visibility underwater. These particles scatter and absorb light, leading to reduced visibility.