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Section T T index 551-559 of 589 terms Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Next turbulence spectrum—A plot of the energy distribution of turbulent eddies versus wavelength or frequency.           Wyngaard, J. C., 1973: On surface-layer turbulence. Workshop on Micrometeorology, D. E. Haugen, Ed., AMS, p. 132. turbulence—1. Irregular fluctuations occurring in fluid motions. It is characteristic of turbulence that the fluctuations occur in all three velocity components and are unpredictable in detail; however, statistically distinct properties of the turbulence can be identified and profitably analyzed. Turbulence exhibits a broad range of spatial and temporal scales resulting in efficient mixing of fluid properties. Analysis reveals that the kinetic energy of turbulence flows from the larger spatial scales to smaller and smaller scales and ultimately is transformed by molecular (viscous) dissipation to thermal energy. Therefore, to maintain turbulence, kinetic energy must be supplied at the larger scales. See also ocean mixing. 2. Random and continuously changing air motions that are superposed on the mean motion of the air. See aircraft turbulence.           Fleagle, R. G., and J. A. Businger, 1980: An Introduction to Atmospheric Physics, 2d ed., Academic Press, p. 264.           Frisch, U., 1995: Turbulence: The Legacy of A. N. Kolmogorov, Cambridge University Press, 1–22.           Hinze, J. O., 1975: Turbulence, 2d ed., McGraw–Hill, 790 pp. turbulent boundary layer—An atmospheric boundary layer containing a range of quasi-random eddies or swirls that tend to cause mixing and dispersion of tracers within it. Most atmospheric boundary layers form on earth because of turbulence acting in a statically stable troposphere. turbulent diffusion—(Or eddy diffusion.) Diffusion or dispersion due to the effects of turbulent motions. When quantifying turbulent diffusion, it is important to distinguish between two types of measurement: 1) single-particle diffusion, where we measure the distances between diffusing particles at a fixed point or a point moving with the mean fluid velocity, and where the mean-square particle displacement initially increases rapidly with time (e.g., linearly); and 2) two-particle diffusion, where we measure the distances between particle pairs or the dimensions of a cloud of diffusing particles. Here the mean-square distance initially increases more slowly (e.g., as the 5/ 2 power of the time). turbulent dissipation—See dissipation. turbulent exchange—See eddy flux. turbulent flow—A fluid flow characterized by turbulence. See eddy, laminar flow, transitional flow. turbulent flux—Transport of a quantity by quasi-random eddies or swirls; the covariance between a velocity component and any variable. For example, time series of potential temperature θ and vertical velocity w can be used to find the turbulent vertical kinematic heat flux, FH: where there are N data points in each time series, i is the time-series data index, primes denote deviations from the mean (i.e., the turbulent gusts), and the overbar denotes an average over the whole time series. turbulent shear stresses—Same as Reynolds stresses. turbulent transfer coefficients—See exchange coefficients. Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Next