hurricane vs tropical storm

hurricane

noun
  • A severe tropical cyclone in the North Atlantic Ocean, Caribbean Sea, Gulf of Mexico, or in the eastern North Pacific off the west coast of Mexico, with winds of 119 km/h (74 miles per hour) or greater accompanied by rain, lightning, and thunder that sometimes moves into temperate latitudes. 

  • A wind scale for quite strong wind, stronger than a storm 

  • "full—triple-full—full" – an acrobatic maneuver consisting of three flips and five twists, with one twist on the first flip, three twists on the second flip, one twist on the third flip 

tropical storm

noun
  • A cyclone within the tropics, typically having its thunderclouds organized in a spiral shape with wind speeds on the surface between about 30 and 75 miles (60 - 120 km) per hour. 

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