Hair particles laying flat on hills I am trying to make grass using hair particles. When I add hills to my scene the grass/hair lays flat - I need them to stay vertical.

Here's a picture and my .blend file. What's going on? I have looked everywhere for an answer over the past 3 days. 

blend file
In the particle panel, click on advanced, then in the velocity section, lower the normal strength and grow the Z strength :