diurnal tide
96
diurnal tide tide with high water and low water only once in the course of
(approximately) one day, as for instance in southeast Asian waters.
--?harmonic analysis of tides.
divergence/convergence (phys.) the expansion/contraction of a transported
property like mass or heat. In the continuity equation the divergence of mass is
zero. Often divergence is related to a source and convergence to a sink. In a
two-dimensional plane like the sea surface, the current may show a divergent or convergent pattern, but as this brings about vertical motion, and
thus no three-dimensional divergence or convergence, the terms diffluence or
confluence should be preferred.
divergent plate boundary --?plate boundary.
Divergence. (After Scharnow
1978)
divers (bioI.) animals that catch their food by diving, e.g., whales, some seabirds.
diversity term used for the degree to which the total number N of individual
organisms in a given ecosystem, area, community or trophic level is divided evenly over different species. Diversity is minimal when all organisms are of the
same species, as, e.g., in a monoculture or (almost) in intensive agriculture.
Diversity is maximal in stable natural environments with a maximal variation in substrate and life conditions (or, where the number of niches is maximal), as, e.g., on coral reefs in the tropical oceans. Diversity can be expressed
quantitatively by a diversity index. There are several types. The simplest is:
diver-sity d = S/log2N, where S is the total number of species. The Margalef
index d= (S-l)/lnNis a modification, with minimum value d= 0 for a monoculture. More complicated indices of diversity are used when it is also taken
into account that there are different distributions possible of the total number
of individuals N over the number of species S, or in other words, when the
concepts evenness or dominance are introduced (an even distribution means
maximal evenness, while the opposite is maximal dominance of the single
species making the whole system). When, moreover, the concept richness (the
96
diurnal tide tide with high water and low water only once in the course of
(approximately) one day, as for instance in southeast Asian waters.
--?harmonic analysis of tides.
divergence/convergence (phys.) the expansion/contraction of a transported
property like mass or heat. In the continuity equation the divergence of mass is
zero. Often divergence is related to a source and convergence to a sink. In a
two-dimensional plane like the sea surface, the current may show a divergent or convergent pattern, but as this brings about vertical motion, and
thus no three-dimensional divergence or convergence, the terms diffluence or
confluence should be preferred.
divergent plate boundary --?plate boundary.
Divergence. (After Scharnow
1978)
divers (bioI.) animals that catch their food by diving, e.g., whales, some seabirds.
diversity term used for the degree to which the total number N of individual
organisms in a given ecosystem, area, community or trophic level is divided evenly over different species. Diversity is minimal when all organisms are of the
same species, as, e.g., in a monoculture or (almost) in intensive agriculture.
Diversity is maximal in stable natural environments with a maximal variation in substrate and life conditions (or, where the number of niches is maximal), as, e.g., on coral reefs in the tropical oceans. Diversity can be expressed
quantitatively by a diversity index. There are several types. The simplest is:
diver-sity d = S/log2N, where S is the total number of species. The Margalef
index d= (S-l)/lnNis a modification, with minimum value d= 0 for a monoculture. More complicated indices of diversity are used when it is also taken
into account that there are different distributions possible of the total number
of individuals N over the number of species S, or in other words, when the
concepts evenness or dominance are introduced (an even distribution means
maximal evenness, while the opposite is maximal dominance of the single
species making the whole system). When, moreover, the concept richness (the