To cite the 'humidity' package in publications use:

Jun Cai (2018). humidity: Calculate Water Vapor Measures from Temperature and Dew Point. R package version 0.1.4.

Corresponding BibTeX entry:

  @Manual{,
    title = {humidity: Calculate Water Vapor Measures from Temperature
      and Dew Point},
    author = {Jun Cai},
    year = {2018},
    note = {R package version 0.1.4},
    url = {https://github.com/caijun/humidity},
  }