Buoyant or buoyancy is relative to the sinking or floating characteristics of an object in liquids. We can say objects are positively buoyant or have a positive buoyancy when they float. Inversely are negatively buoyant when they sink, and neutrally buoyant when they neither float or sink and remains at the same depth.
Normoxic is the name given to a breathing gas mix for which the percentage or fraction of oxygen is similar to the one of air, but contain a different mix of other gases. Along with hypoxic and hyperoxic, normoxic is one of the three kinds of breathing gas mixes for diving.
Hyperoxic is a term used for breathing gases that has a higher percentage or fraction of oxygen than regular air. The term or word is not so commonly used because of the designation Nitrox or Enriched Air, which is used instead to cover hyperoxic gases. It is the opposite of hypoxic.
The work of breathing or WOB is in simple terms, the effort required by the lungs to breathe. But to be more accurate it refers to the energy expended to inhale and exhale a breathing gas. The WOB is usually expressed as work per unit volume.
The process known as “upwelling” is caused by the winds blowing across the surface of the ocean and push water away. Colder water then rises up from deeper beneath the surface to take the place of the water that was pushed away. It is also the opposite of downwelling.
A quick release is a form of clip used for diving equipment. It is usually associated with a weight system but applies to many other purposes such as the releases of shoulder straps.
A rattle in diving is a piece of equipment designed to get attention by making a rattling sound. It is usually a hollowed tube with both ends plugged and containing metal balls. Shaking it create a sound from the shock of the balls.
lb or lbs are the short unit designation for pounds. It is a measurement of weight coming from the imperial system of units. One pound is equal to exactly 0.453592 kilograms.
Hypercapnia is defined as an increase of carbon dioxide in the body which leads to faster breathing rate and heartbeat as the body is trying to eliminate it.
Heliox is a breathing gas mixture used in technical and commercial diving. Heliox is composed of Oxygen and Helium only. Having no Nitrogen it avoid nitrogen narcosis that happens in deeper dives.