what is negative angle of attack?
 

Hi, all
I am a biginner of aeronautics. In the book, I studied the angle of attack is the angle between cord line of aerofoil and the relative wind. However, what does negative angle of attack means?
I appreciate for your kindly help.

well, a positive angle of attack is what is normally experienced with the leading edge 'higher' than the trailing edge of the aerofoil (with the camber upwards). A negative angle of attack would be the reverse (including inverted flight).

I think that's a bit better :)

and what if you are inverted?just expanding....