So tell me...does wind blow, or does wind suck? No, really, I want to know!

I was contemplating this the other day and thoroughly confused myself. How can you tell if the pressure system equalization process is pushing from one direction or pulling from the other? My Kirby vacuum clealer sucks, but if you watch the debris that gets caught in the vacuum, it looks just like its blowing in the wind.... well untill it dis-appears anyway.

If you can clearly convince me one way or the other (and I don't convince easily...I'm kinda dense), I've got a few more confusing questions.