Energy Transmission through Water – Light

Vocabulary and core concepts regarding the transmission of light energy through seawater, covering the electromagnetic spectrum, absorption characteristics, and optical phenomena like refraction and scattering.

Visibility (the viz)

A term used by divers, such as those from the Professional Association of Diving Instructors (PADI), to describe how far they can see in the water.

Light energy

A combination of changing electrical impulses moving in the form of waves and changing magnetic fields around those electrical impulses, radiating from the sun through the vacuum of space at the speed of light.

Electromagnetic spectrum

The full range of energy waves formed by simultaneous electrical and magnetic oscillations, spanning from low energy radio waves to high energy gamma rays, including visible light.

Wavelengths shorter than visible light

Segment of the electromagnetic spectrum that includes ultraviolet rays, x-rays, and gamma rays.

Wavelengths longer than visible light

Segment of the electromagnetic spectrum that includes infrared waves, microwaves, TV, FM and AM broadcast band waves, and long radio waves.

Visible light

A narrow segment of the electromagnetic spectrum, approximately $400-750\,nm$, consisting of rainbow colours (violet, indigo, blue, green, yellow, orange, and red) that the human eye can perceive.

Light reflection

The process where light strikes a smooth or shiny surface and bounces off at the same angle as it hit the surface.

Light penetration

A measure of how deep light or electromagnetic radiation can travel into a medium; in water, $60\%$ is absorbed within the first $1\,metre$ and $80\%$ by the $10th\,metre$.

Light scattering

The deflection of wave energy in multiple directions due to imperfections or suspended particles, such as sediment or organic matter, in a medium.

Light absorption

The process where light strikes an object and is converted to thermal energy; in seawater, longer wavelengths like red, orange, and yellow are absorbed first and do not reach a depth of $10\,metres$.

Light attenuation

The reduction in light intensity as it passes through a medium due to the combined effects of absorption and scattering.

Light refraction

The bending of light as it passes from one medium to another of different density, which causes a change in the speed of the light ray.

Wavelength

In a progressive electromagnetic or sound wave, the horizontal distance measured between two successive troughs or two successive crests.

Emit

To discharge, give out, or give off.

Opaque

The property of a surface that is not translucent or transparent, thereby preventing light from traveling through it.

Penetrability

The ability of a material or medium to be penetrated.