It is always the 3rd ring used in the process of summoning him. The Wind Ring is responsible for Captain Planet's flight ability and presumably his hurricane-like breath and the ability to create wind-based weather conditions. It has the unique ability out of all the magic rings to be able to create and manipulate its element, as opposed to the others which can do either or but not both. It can also be used to create gusts of wind to aid in transport in various types of transportation such as a sailboat.
However, it is very draining on Linka when she engulfs herself with wind enabling her to fly momentarily. It can create small whirlwinds, open some barricaded doors, blow away objects and gases, and lift people including the user to new heights. The Wind Ring gives its holder control over the element of Wind to a limited degree.