Die Isothermkurven der Nordlichen Halbkugel [Isotherm Curves of the Northern Hemisphere]

German interpretations of von Humboldt’s work on isotherms.

This striking copperplate engraved map, published in 1838 by the renowned firm of Justus Perthes, represents an important moment in the history of climatology. It was issued as part of the groundbreaking Physikalischer Atlas, a monumental collaborative effort led by Heinrich Berghaus to systematically map the natural world’s physical phenomena.

The finely detailed image utilizes isothermal lines, a revolutionary cartographic concept pioneered by Alexander von Humboldt, to connect points across the Northern Hemisphere sharing the same mean annual temperature. By visually demonstrating how continental landmasses and ocean currents cause these thermal bands to deviate from simple lines of latitude, the work offers a radical new understanding of global climate relationships. Profiles of the tallest mountains (critical elements of von Humboldt’s theories) are provided along the bottom of the page.