[cameldrv]

You've really got three regimes. Really big things are ballistic in your sense that the dominant force is gravity. Smaller things are also sensitive to bulk air movement. Really small things aren't affected much by gravity, and brownian motion is more important.

When these guys are saying "ballistic", they mean that the droplet is big enough that gravity is important, and that it's going to hit the ground in a reasonable amount of time and not hang around in the air until convection/diffusion spread it evenly throughout the room.