Isopleth

An isopleth is a line of equal or constant value on a map or grid of varying quantities.

Different types of isopleth are given different names according to the nature of the quantity involved:

• pressure: isobar.
• temperature: isotherm.
• dew point: isodrosotherm.
• humidity: isohume.
• wind speed: isotach.
• wind direction: isogon.
• liquid precipitation amount: isohyet

"iso" can be replaced with "isallo" to give it the meaning of a line connecting points where some variable has changed at the same rate during some time period.

Synonyms: isogram, isarithm

External Links

• Drawing Contour Plots (http://avc.comm.nsdlib.org/cgi-bin/wiki_print.pl?Drawing_Contour_Plots). A lesson plan that deals with drawing various isopleths.

• See also Forthright's Phrontistery (http://phrontistery.50megs.com/contour) for many more different types of isopleths.