roughness vs turbulence

roughness

noun
  • The property of being rough, coarseness. 

  • A measure of how rough something is, such as a surface 

  • Abundance, especially of food. 

  • Roughage; coarse fodder. 

  • Something that is rough; a rough spot. 

turbulence

noun
  • The state or fact of being turbulent or agitated; tempestuousness, disturbance. 

  • Disturbance in a gas or fluid, characterized by evidence of internal motion or unrest. 

  • Specifically, a state of agitation or disturbance in the air which is disruptive to an aircraft. 

  • An instance or type of such state or disturbance. 

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