The area in a valley where water runs. Usually referred to with open valley configurations.
Water turbine
A turbine that uses water pressure to rotate its blades; the primary types are the Pelton wheel, for high heads (pressure); the Francis turbine, for low to medium heads; and the Kaplan for a wide range of heads. Primarily used to power an electric generator.
Water vapor
Water vapor can be treated as a gas. At a particular temperature air for example can only hold so much water vapor. The higher the temperature the more water vapor it can hold. When saturated the relative humidity would be 100 % RH, so relative humidity describes how close to saturation the air is. It is important to remember that in a process with a high relative humidity a small drop in temperature will cause the humidity to rise and the environment to saturate. Rapid temperature changes in a an environmental chamber for example could also cause condensation.
Water wall
An interior wall made of water filled containers for absorbing and storing solar energy.
Water wheel
A wheel that is designed to use the weight and/or force of moving water to turn it, primarily to operate machinery or grind grain.
Water-holding capacity
Amount of water able to be retained in an expansion tank or other type of unit.
Water-thinned paint
Paint which uses water as a vehicle.
Waterfront property
Structure adjacent to a lake or other type of water, which has a higher sale value due to greater demand.
Waterproof
Being resistant to moisture infiltration.
Waterproof switch
Electrical switch that is sealed so that the outside elements don't enter it. Gas tights seals would make it explosion proof.
