air raid vs shelling

air raid

noun
  • An attack on a surface target by aircraft. 

  • A passing-heavy offensive scheme based on a shotgun formation with four wide receivers and a single running back. 

shelling

noun
  • An artillery bombardment. 

  • The removal of the shell from a nut, pea etc. 

  • Shallow, irregular cracks that appear on the surface of a coating such as plaster or mortar. 

  • An ordering of the facets of a boundary complex such that the intersection of each facet (other than the first) with the union of all preceding facets is homeomorphic to a ball or sphere. See Shelling (topology) 

  • Grain from which the husk has been removed. 

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