Here is something I call a "Sitting Wave":
like when you receive from a superhet radaradio all the way down to zero cycles per second.
See how it stays about the same strength, rather than dissappearing to straight and then reappearing to wavy over and over again.
Sitting waves are more relaxed than standing waves. Rather than jumping up and down, they stay more still.
That's why I like to sit down when I make sitting waves on my POVARbotTM.
See my father's examples of sitting waves, from 1974:
See my father's example of sitting waves, from 2015: