air raid vs bombardment

air raid

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

  • An attack on a surface target by aircraft. 

bombardment

noun
  • heavy artillery fire 

  • the act of bombing, especially towns or cities 

  • the incidence of an intense stream of high-energy particles directed at a substance 

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