dispersion

views updated May 08 2018

dispersion
1. The spreading of a body of water as it flows. Lateral dispersion is the widening of the path taken by ground-water as it flows from a known point of origin through a rock matrix, due to its movement around individual mineral grains within the main rock body. Unless it flows in well-defined fissures or fractures, water does not travel through a rock in a straight line but is forced to flow across a widening front because of the granular nature of the rock matrix. Longitudinal dispersion is the spreading out of a body of water along its own flow path, due to the differences in water velocities in larger and smaller pores of the rock. Both modes of dispersion are normally observed by means of tracers. Lateral and longitudinal dispersion also occur in river channels, where they are due to differences in flow velocity across the channel and between the water surface and the bed, and also to random fluctuations in velocity caused by turbulent eddies.

2. The process of separating soil particles (as in aggregates) from each other so that they may react as individual particles. Aggregates or peds of soil particles are destroyed by dispersion (and their formation is initiated by flocculation.

3. The distortion of a wave train that occurs when velocity varies with frequency and consequently the phase velocity is not the same as the group velocity. There is minimal dispersion for most body waves (although electromagnetic body waves are subject to considerable dispersion) but it is important for surface waves, especially Love waves, particularly in the presence of velocity-layering near the surface.

4. In mineral optics, a measure of the difference in refractive index, determined by direct observation of the biaxial interference figure using the two extreme wavelengths of the visible spectrum (red and violet). Both isogyres are observed for red and violet tints.

5. See SWELL.

dispersion

views updated May 29 2018

dispersion
1. In statistics, the internal pattern of a population (i.e. its distribution about the mean value). In spatial statistics, the pattern relative to some specific location, or of individuals relative to one another (e.g. clumped or random).

2. In pedology, the process of separating soil particles (as in aggregates) from each other so that they may react as individual particles. Aggregates or peds of soil particles are destroyed by dispersion (and formation is initiated by flocculation).

3. The spreading of a body of water as it flows. Lateral dispersion is the widening of the path taken by groundwater as it flows from a known point of origin through a rock matrix, owing to its movement around individual mineral grains within the main rock body. Unless it flows in well-defined fissures or fractures, water does not travel through a rock in a straight line but is forced to flow across a widening front because of the granular nature of the rock matrix. Longitudinal dispersion is the spreading out of a body of water along its own flow path, due to the differences in water velocities in larger and smaller pores of the rock. Both modes of dispersion are normally observed by means of tracers. Lateral and longitudinal dispersion also occur in river channels, where they are caused by differences in flow velocity across the channel and between the water surface and the bed, and also by random fluctuations in velocity caused by turbulent eddies.

4. See swell.

dispersion

views updated May 23 2018

dispersion
1. In statistics, the internal pattern of a population, i.e. its distribution about the mean value. In spatial statistics, the pattern relative to some specific location, or of individuals relative to one another, e.g. clumped or random.

2. In pedology, the process of separating soil particles (as in aggregates) from each other so that they may react as individual particles. Aggregates or peds of soil particles are destroyed by dispersion (and formation is initiated by flocculation).

dispersion

views updated May 29 2018

dispersion In statistics, the internal pattern of a population, i.e. its distribution about the mean value. In spatial statistics, the pattern relative to some specific location, or of individuals relative to one another, e.g. clumped or random.

dispersion

views updated May 11 2018

dispersion See measures of variation.