Raindrops keep falling on my head...

As a result of speeding through the atmosphere because of gravity, Raindrops have a more flattened bottom and rounded top until they are ripped apart when they approach 5 mm.

USGS Water Science for Schools

Growing up on the West Coast of Canada you get passionate about the rain because it is one of the only things that is constant in your life.  Check out this article on about.com about raindrops that is much like I said in this post.