I once saw a site that showed budding young film directors how to make a machine that created 'movie rain.' This machine was needed because real rain was notorious for not showing up on film.
While this photo doesn't prove things to be otherwise, it does show that it's not an absolute. If it rains hard enough, it will show up, as can be seen if you view the larger version of this photo.
Anyway, I was just surprised to see the raindrops. Nothing else special about it I guess.