airship vs weather balloon

airship

noun
  • A lighter-than-air aircraft that can be propelled forward through the air as well as steered. 

  • A police air unit, a police helicopter 

  • Any aircraft. 

  • A high ranking official of the RAF, viewed as arrogant and distant. 

verb
  • To transport goods by aircraft. 

weather balloon

noun
  • a balloon that carries meteorological instruments aloft in order to measure, record and return data concerning atmospheric pressure, temperature and humidity 

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