graupel vs snowfield

graupel

noun
  • A precipitation that forms when supercooled droplets of water condense on a snowflake. 

  • The result of this process, a small ball of rime. 

snowfield

noun
  • A large permanent expanse of snow on a mountain or at the head of a glacier. 

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