The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(also isolines), lines of equal value of some magnitude in its distribution on a surface, in particular on a plane (geographic map, vertical cross section, or graph). Isograms reflect continuous change in the quantity under investigation as a function of two other variables, for example, of geographic latitude and longitude on maps. Table 1 lists some isograms.

Isograms on maps are used most extensivey to characterize the values of continuous quantities and quantities that change gradually in space (for example, air temperature). However, they also perform much more varied functions. They are used on maps to indicate change in the quantitative characteristics of phenomena with time (for example, secular changes in the components of the earth’s magnetism), the rate of change of phenomena (for example, wind velocity), the time of occurrence of certain phenomena (for example, the onset of the first autumn frosts), the duration of phenomena (for example, the number of days with snow cover), the orientation of some physical quantities (for example, magnetic declination), and the frequency or probability of phenomena (for example, the frequency of thunderstorms). If at least one of the independent variables is some quantity other than a geographic coordinate, then the isograms are called isopleths.


Table 1. The most common isograms
1 The part of the term after the prefix is of Greek origin unless otherwise indicated
NameEtymology1Phenomenonbeing described
Hydroisobathbathos, “depth”Depth of groundwater table
relative to earth’s surface
Hydroisohypsehypsos, “height”Elevation of groundwater
table above sea level
Hydroisopiesospiezo, “I press”Pressure of artesian waters
Isallobarsbams, “weight”Change in atmospheric
pressure per unit time
Isallohypsehypsos, “height”Change in elevation of
isobaric surface per unit
therme, “heat”Change in air temperature
per unit time
“incommensurable,” “irregular”
Same as isanomal
Latin amplitudo, “magnitude”Amplitude of change in meteorological elements
over some interval of time.
anemos, “wind”Average wind velocity over
some period of time
anomalos, “irregular”Deviation of some quantity
(temperature, amount of
precipation) from value
adopted as norm (average
long-term, average latitudinal)
Isoanthoanthos, “flower,”
Times when certain plants
Isoatmosphereatmos, “vapor,”
Magnitude of evaporation or
evaporability for a certain
time interval
Isobasebasis, “stepping,”
ana, “upward”
cata, “downward”
Magnitude of tectonic
movements (uplifts—
isanabases–or subs-
idences—isocatabases) over
some interval of time
Isobarbaros, “weight”Atmospheric pressure
Isobathbathos, “depth”Depth of bodies of water
Isobrontbronte, “thunder”Number of days with
Isochronechronos, “time”Times of occurrence of
some phenomenon
Isoclinic line klino, “I lean”Magnitude of magnetic clip
Isodynamic linedynamis, “force”Full intensity of the earth’s
magnetic field or its
Isogonic linegonia, “angle”Orientation of certain
physical quantities
(magnetic declination, wind
Isohalinehals, “salt”Salinity of waters
Isohionchion, “snow,” “snow
Thickness or duration of
snow cover
Isohyethyetos, “rain”Amount of precipitation in a
certain period
Isohypse (horizontal)hypsos, “height”Elevation of the earth’s
surface above sea
Isonephnephos, “cloud”Cloudiness
Isopachpachys, “thick,”
Thickness of geological
strata of certain age or
Isophase Greatest phases of solar
Isophenephaino, “I show”Times or duration of certain
phenological phases
Isoporpoms, “path,”
Secular changes in components
of earth’s magnetism
Isorhachic linerhachia, “surf,” “ocean
Elevation of ocean tides
Isoseismalseistos, “set to oscillat-ing,”
Intensity of earthquakes
Isotacteko, “I melt”Times when frozen inland
waters thaw
Isotachtachos, “speed”Velocity of currents
Isothermtherme, “heat”Temperature of air, water, and soil
Isothermobaththerme, “heat”
bathos, “depth”
Water temperature in the
depths of bodies of water
IsovelLatin velox, “quick”Same as isanemone
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The variation characteristics and the range of the periodic changes of the select measures at different time-scales can be analyzed based on the isograms about [W.sub.f](a, b).
Caption: Figure 4: Isograms of gas volume fraction at sections of the face.
To describe the spatiotemporal evolution of infiltration behaviors, saturation isograms were drawn by each discrete point of degree of saturation (%), which was transformed from volumetric water content measured by TRIME-TDR probes and mass water content measured by soil sampling.
The pressure isograms of the tube-loaded explosion were shown in Figure 10.
In addition, synchronously applying of the other capabilities of this software and Excel 10 program, the map of isograms was drawn and prepared.
Selecting 85%, 95%, and 98% as the intrazone, mesozone, and external zone of the anomaly, the isograms of the raw data and separated data are depicted using the cumulative frequency method.
At Figs 2 and 3 isograms of the maximum and the minimum elongation of the most important horizontal deformations are provided.
The third is the ludic mode, which relates to my liking for constraints, exploits and "exercises" and gives rise to all the work based on the notions and devices gleaned from Oulipo's experiments: palindromes, lipograms, pangrams, anagrams, isograms, acrostics, crosswords, and so on.
As before, Noah turns away hyphenated words, coinages, palindromes, tautonyms and pair isograms.
For example, poems 50, 125, and 162 are isograms on the initial letter (i.e., the same letter figures at the head of each of the eleven permutations); poems 78 and 123 are isograms on the final; poem 24 is an isogram on the diagonal (top left to bottom right), and poem 26 an isogram on the reverse diagonal.
I especially enjoyed the Shortz contest Puder's books ad (I may avail myself of some of them.), Eckler's trigrams, Kickshaws as usual, Dave's palindrome contest, your Melencolia, the Grant and Kahan puzzles, Ray Love's Playful Poems and Danyl Francis' new isograms. Dany's keyboard articles were also informative.
The third is the ludic mode, which relates to my liking for constraints, exploits, "exercises," and gives rise to all the work based on the notions and devices gleaned from OuLiPo's experiments: palindromes, lipograms, pangrams, anagrams, isograms, acrostics, crosswords, etc.