Module 9: Isarithmic Mapping

This week's assignment involved generating isarithmic maps, which are thematic maps often used to depict continuous spatial phenomena. Rainfall is a phenomenon that varies in such a manner based on regional climate and geologic features.  Above are two maps of average annual precipitation in Washington over a 30 year period.  The top map uses continuous tone symbology in which each point (cell) on the map has a corresponding value, and the values vary continuously over the landscape.  The bottom map, which also contains contours of precipitation values, uses only hypsometric symbology in which precipitation ranges are represented by corresponding colors.  Overall, isarithmic maps are useful thematic maps for continuous phenomena, but are limited to these usages.