- 行业: Earth science
- Number of terms: 10770
- Number of blossaries: 1
- Company Profile:
The UK charity dedicated to the protection of the marine environment and its wildlife.
A hump-shaped wave of permanent form. Solitary waves are well known for their tendency to travel long distances without dispersion and, despite being large amplitude (so that linear superposition principles do not apply) colliding waves effectively pass through each other.
Industry:Earth science
A land area where precipitation runs off into streams, rivers, lakes, and reservoirs. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Large drainage basins, like the area that drains into the River Severn contain thousands of smaller drainage basins.
Industry:Earth science
An instability associated with flows with vertical shear and meridional temperature gradients that grows by conversion of potential energy in the mean flow.
Industry:Earth science
A sea-surface wave which has become too steep to be stable. Waves in shoaling water become higher and shorter (hence steeper) as the water becomes shallower. When the steepness (ratio of wave height to wave length) exceeds 1/7, the laws which govern surface-wave motion can no longer be satisfied and the crest of the wave outraces the body of the wave to form a foaming white turbulent mass of water called a breaker. Roughly, three kinds of breakers can be distinguished, depending primarily on the gradient of the bottom: ( a) spilling breakers = (over nearly flat bottom) which form a foamy path at the crest and break gradually over a considerable distance; ( b) plunging breakers (over fairly steep bottom gradient) which peak up, curl over with a tremendous overhanging mass, and then break with a crash; ( c) surging breakers (over very steep bottom gradients) which do not spill or plunge but surge up the beach face. Waves also break in deep water if they build too high while being generated by the wind, but these are usually short-crested and are termed whitecaps .
Industry:Earth science
A tide in which there is only one high water and one low water each lunar day .
Industry:Earth science
In a continuously stratified fluid, the buoyancy frequency is the natural frequency of vertical oscillation of fluid parcels. Explicitly the squared buoyancy frequency is N^2 = -(g/\rho) d\rho/dz, in which g is the acceleration due to gravity and \rho(z) is density as a function of height z.
Industry:Earth science
An approximation to turbulent flow whereby the net effect of molecular diffusion enhanced by strain flows between eddies is parametrized by an eddy viscosity acting on large scale motion. Eddy viscosity may be taken as constant or dependent on the length scale of motion. The former case is equivalent to assuming that the Reynolds stresses are proportional to the gradients of the large scale flow velocity.
Industry:Earth science
A map delineating the form of the bottom of a body of water, usually be means of depth contours ( isobaths ).
Industry:Earth science
An approximation to the dynamical equations of motion whereby density is assumed to be constant except in the buoyancy term, -g\rho', of the vertical velocity equation. The approximation is reasonable if the vertical extent of the dynamics being considered is much smaller than the density scale height - the height over which the density changes by a factor e. It is generally applicable to most oceanographic circumstances. If a system does not satisfy the Boussinesq approximation it is said to be non-Boussinesq.
Industry:Earth science
A localized chaotic movement of air or liquid in a generally uniform larger flow.
Industry:Earth science
