Answer:
A kind of weather that comes your way, but add a "D" and it will run away
What is it which builds things up? Lays mountains low? Dries up lakes, and makes things grow? Cares not a whim about your passing? And is like few other things, because it is everlasting?
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
What is it that makes tears without sorrow and takes its journey to heaven?
The sharp slim blade, that cuts the wind. What is it?
I break away from my pack. I create holes in my victims. I can travel for miles and then disappear. I am part of a dying breed. What am I?