Isotherms for Months of Year

Name: Isotherms for Months of Year
Creator: Natural Resources Canada
License: https://open.canada.ca/en/open-government-licence-canada

Contained within the 2nd Edition (1915) of the Atlas of Canada is a plate comprised of 12 maps of isothermal lines. One map for each month of the year. These lines are drawn at intervals of 5 degrees Fahrenheit. The isolines were deduced from yearly observations collected by the Meteorological Service.