water quality
342
ity diagrams (or T -S diagrams) are used. Homogeneous water masses are represented by a single point in such a T-S diagram, and are labeled by names
indicating their source and level of occurrence. In such diagrams combinations of temperature and salinity measured at successive depths typically lie
along curves that can be considered mixtures of two or more water types.
water quality an arbitrary term for the degree of contamination of water.
-tcontaminant.
watersprout wind vortex with the shape of a funnel reaching the water surface
from a Cumulonimbus (thunderstorm) cloud, and pulling water from the
water surface. Usually its radius is only some 100 m large. A watersprout
results from strong atmospheric instability.
wave commonly used in oceanography for the small-wavelength surface gravity
waves, but physically also used for other wave phenomena. Waves can be
divided into transversal waves (where the disturbance is at right angles to
the direction of propagation) such as sea waves and large-wavelength tides,
and into longitudinal waves (where the disturbance is in the direction of
propagation). To this last category belong the acoustic waves, where the
compressibility of the water is important. Mathematically the waves are
described by a set of wave characteristics. -tseismic wave.
wave approach waves approaching the coast enter shallower water (shoaling of
waves). At an abrupt change in depth, partial reflection in waves may occur.
Gradual decrease in depth causes refraction of obliquely approaching waves.
The wave characteristics will change when depth decreases. After a first slight
decrease in wave height closer to the coast the height and steepness of the
waves increase until they become unstable and break (breaking of waves)
Empirically it has been found that this occurs at a depth of l.2 times the
wave height. The action of the waves after breaking is called the surf. By inertia the water runs up the shoreline (swash) and returns back along the slope
(backwash) .
wave characteristics describe a wave mathematically. Apart from the wavelength
L, the amplitude A and the period T, the wave number k=2nlL and the angular frequency w = 2nlT are used. Individual progressive (gravity) waves move
with a phase speed c = wlk = LIT. Generally, this speed is a function of depth
and wave characteristics, but for relatively deep water it becomes depthindependent (-tshort wave). For relatively shallow water (-tlong wave) the
phase speed is only a function of depth (D) and gravity (g) : c = $if5). As
wave energy propagates with a speed that depends on phase speed, most gravity waves, except long waves, have a wave number-dependent propagation,
and are subject to dispersion. -twind wave.
342
ity diagrams (or T -S diagrams) are used. Homogeneous water masses are represented by a single point in such a T-S diagram, and are labeled by names
indicating their source and level of occurrence. In such diagrams combinations of temperature and salinity measured at successive depths typically lie
along curves that can be considered mixtures of two or more water types.
water quality an arbitrary term for the degree of contamination of water.
-tcontaminant.
watersprout wind vortex with the shape of a funnel reaching the water surface
from a Cumulonimbus (thunderstorm) cloud, and pulling water from the
water surface. Usually its radius is only some 100 m large. A watersprout
results from strong atmospheric instability.
wave commonly used in oceanography for the small-wavelength surface gravity
waves, but physically also used for other wave phenomena. Waves can be
divided into transversal waves (where the disturbance is at right angles to
the direction of propagation) such as sea waves and large-wavelength tides,
and into longitudinal waves (where the disturbance is in the direction of
propagation). To this last category belong the acoustic waves, where the
compressibility of the water is important. Mathematically the waves are
described by a set of wave characteristics. -tseismic wave.
wave approach waves approaching the coast enter shallower water (shoaling of
waves). At an abrupt change in depth, partial reflection in waves may occur.
Gradual decrease in depth causes refraction of obliquely approaching waves.
The wave characteristics will change when depth decreases. After a first slight
decrease in wave height closer to the coast the height and steepness of the
waves increase until they become unstable and break (breaking of waves)
Empirically it has been found that this occurs at a depth of l.2 times the
wave height. The action of the waves after breaking is called the surf. By inertia the water runs up the shoreline (swash) and returns back along the slope
(backwash) .
wave characteristics describe a wave mathematically. Apart from the wavelength
L, the amplitude A and the period T, the wave number k=2nlL and the angular frequency w = 2nlT are used. Individual progressive (gravity) waves move
with a phase speed c = wlk = LIT. Generally, this speed is a function of depth
and wave characteristics, but for relatively deep water it becomes depthindependent (-tshort wave). For relatively shallow water (-tlong wave) the
phase speed is only a function of depth (D) and gravity (g) : c = $if5). As
wave energy propagates with a speed that depends on phase speed, most gravity waves, except long waves, have a wave number-dependent propagation,
and are subject to dispersion. -twind wave.