## Nordenskjöld line

The line connecting all places at which the mean temperature (°C) of the warmest month is equal to 9 - 0.1

*k*, where*k*is the mean temperature of the coldest month. (In degrees Fahrenheit the relationship becomes 51.4 - 0.1*k*.)This line fits the arctic tree line better than any other purely climatic isopleth hitherto tried.

Hare, F. K. 1951. Compendium of Meteorology. p. 955.