evaporation vs vapour

evaporation

noun
  • The process in which all or a portion of liquid (in a container) is turned into vapour, in order to increase the concentration of solid matter in the mixture. 

  • The process of a liquid converting to the gaseous state. 

vapour

noun
  • British standard spelling of vapor. 

verb
  • British standard spelling of vapor. 

How often have the words evaporation and vapour occurred in a corpus of books? (source: Google Ngram Viewer )