hot air vs portentousness

hot air

noun
  • Empty, confused, or exaggerated talk lacking meaning or substance; bluster. 

  • Air that has been heated, especially so as to function as the lifting agent of a hot-air balloon. 

portentousness

noun
  • The quality of being portentous 

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