Wind Turbine Blades

Not quite sure what you are trying to describe, but here are my observations.

In planform, all seem to have an eliptical shape at the tip.

In airfoil sections used, most seem to have a concave section on the top (side away from the mast) that is visible under proper light conditions (front 2/3 or so of the blade lit up by sunshine, a portion that is dark, then the last 10-15% of the chord is back in sunshine).

Many of the large diameter turbines now have, for lack of a better term, a "dihedral break" in them out near the tip. Near as I can tell, this is primarily for providing blade to mast clearance, as the blade flexes back towards the mast and the designers had a choice between adding mass (to get stiffness), putting a "kink" in the blades, to bend it out away from the mast, or making a new top end with an even longer overhang. Two of those three options add cost and weight and reduce efficiency. The third gets the clearance needed and actually increases the swept area over a blade set that does not have this "dihedral" break in the blade. This "break" is in the range of 15 to 20% of the balde length in from the tip of the blade.

Some of the earlier wind farms in Kansas had roughly 75 foot long blades, and these did not have this feature. The newer ones going in have nearly 100 foot long blades, and they do have this feature. It may look like a "dip", as inboard of this, the blade is bent back towards the mast, and outboard of this, the blade is much more nearly parallel to the mast.