rippling vs undulating

rippling

adj
  • Moving in a chaotic, undulating fashion, as in a flow of water or a flag blowing in the wind. 

noun
  • A motion or sound that ripples. 

undulating

adj
  • Moving up and down like waves; wavy. 

  • Forming a series of regular curves. 

noun
  • undulation 

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