cloud the issue vs overcast

cloud the issue

overcast

noun
  • A cloud covering all of the sky from horizon to horizon; cloudy. 

verb
  • To fasten (sheets) by overcast stitching or by folding one edge over another. 

  • To make gloomy; to depress. 

  • To cover with cloud; to overshadow; to darken. 

adj
  • In a state of depression; gloomy; melancholy. 

  • Covered with clouds; overshadowed; darkened; (meteorology) more than 90% covered by clouds. 

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