liquefaction vs rainfall

liquefaction

noun
  • Process of being, or state of having been, made liquid (from either a solid or a gas) 

  • The liquid or semiliquid that results from this process. 

rainfall

noun
  • The occurrence of liquid precipitation, the fall of rain. 

  • the amount of rain that falls on a single occasion 

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