- 行业: Earth science
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1. Any scattering process produced by spherical particles whose radii are smaller than about one-tenth the wavelength of the scattered radiation. Compare Mie scattering. See also size parameter. In Rayleigh scattering, the scattering coefficient varies inversely with the fourth power of the wavelength, a relation known as the Rayleigh law. The angular intensity polarization relationships for Rayleigh scattering are conveniently simple. For particles not larger than the Rayleigh limit, there is complete symmetry of scattering about a plane normal to the direction of the incident radiation, so that the forward scatter equals the backward scatter.
2. The scattering of light by a body with a particle diameter (Dp) less than 0. 03 micrometers is termed Rayleigh Scattering. The wavelength of light scattered is dependent on the Dp, and the amount of light scattered is dependent on the number of particles present per unit volume. Shorter visible wavelengths, such as blue, are scattered by smaller particles than are the longer wavelengths like red.
Industry:Earth science
A cold ocean current flowing from the Bering Sea southwest along the coast of Kamchatka, past the Kuril Islands, continuing close to the northeast coast of Japan and reaching nearly 35 degrees latitude. The Oyashio turns and continues east eventually jointing the Aleutian current . The cold waters of the Oyashio rapidly mix with those of the northern branch of the Kuroshio extension .
Industry:Earth science
A collection of waves the amplitudes of which have a Gaussian dependence on wavenumber about some central wavenumber.
Industry:Earth science
A continuation of the Gulf Stream , originating at about 40 degrees latitude and 50 degrees longitude, comprising all the easterly and northerly currents of the North Atlantic originating in the region east of the Grand Banks. The branches of the North Atlantic current are often masked by shallow and variable, wind-driven surface movements so that they are sometimes called the North Atlantic drift . Along the mid-Atlantic ridge the North Atlantic current is divided into two major branches; the northern branch flows between latitudes 50 degrees and 52 degrees separated from the Labrador current by the cold wall . The other branch flows approximately in latitude 45 degrees and carries undiluted Gulf Stream water. Of these branches the northern continues mainly toward the east-northeast and divides, part flowing into the Norwegian Sea and part turning toward the north and northwest eventually giving rise to the Irminger current .
Industry:Earth science
A countercurrent of the Pacific Ocean running north along the west coast of the United States (from northern California to Washington to at least latitude 48 degrees) during the winter months.
Industry:Earth science
The ocean current with the largest volume transport (approximately 110 x 10(s) m(s)/sec), and the swiftest current; it flows from west to east through all the oceans around the Antarctic Continent. It is locally deflected from its course, partly by the distribution of land and sea and partly by the submarine topography. Beside the bends that are associated with the bottom topography, the effects of the distribution of land and sea and of the currents in the adjacent oceans are also evident. On its northern edge it is continuous with the South Atlantic current , the South Pacific current and the eastward-flowing extension of the Agulhas current in the Indian Ocean. A flow to the west near the Antarctic Continent is evident only in the Weddell Sea area, where an extensive cyclonic motion occurs to the south of the circumpolar current. antarctic convergence.
Industry:Earth science
A dimensionless number comparing the buoyancy with Coriolis forces. Explicitly, the Burger number is Bu = N<sup>2</sup> D<sup>2</sup>/(f<sup>2</sup> L<sup>2</sup>) in which N is the buoyancy frequency, f is the Coriolis parameter, and D and L are characteristic vertical and horizontal length scales, respectively.
Industry:Earth science
A dimensionless number relating the ratio of buoyancy to inertial forces. In a stratified fluid with characteristic squared buoyancy frequency J,the bulk Richardson number is Ri = J/(U/L)^2 in which U and L are characteristic velocity and length scales. The gradient Richardson number is defined as a function of height for stratified parallel flows by Ri_g (z) = N^2(z)/(dU/dz)^2 in which U(z) is the mean horizontal velocity and N^2(z) is the squared buoyancy frequency as a function of height. The flux Richardson number is defined for stratified turbulent flows with perturbation horizontal and vertical velocity fields u' and w', respectively, by Ri_f = -(g/
ho_0)<
ho'w'>/((dU/dz) ) which is the ratio of the rate of conversion to potential energy by the vertical flux of perturbation density
ho' to the rate of extraction of mean kinetic energy from the background horizontal velocity U(z). The flux Richardson number is also called the mixing efficiency.
Industry:Earth science
A dimensionless number relating the ratio of inertial to buoyancy forces applicable, in particular, to homogeneous shallow water flow, or two layer flow. Explicitly, in the shallow water approximation the Froude number is Fr=U^2/(gH) in which U is the characteristic velocity, H the characteristic fluid depth, and g the acceleration due to gravity.
Industry:Earth science
A dimensionless number relating the ratio of inertial to Coriolis forces. Explicitly, the Rossby number is Ro=U/(fL) in which U and L are characteristic velocity and horizontal length scales, respectively, and f is the Coriolis parameter at a fixed latitude. Flows with sufficiently small Rossby number are in geostrophic balance.
Industry:Earth science
