Smart glider pilots try to give wide berth to thunderstorms. For although the convective air associated with them provides lots of lift, (along with downdrafts too), horizontal lightning can commonly reach 5 to 10 miles from the storm. 20 miles and more is not unheard of.
Aircraft commonly have "static wicks" at the trailing edge of flying surfaces. This, to help bleed off static charges in the airframe that accrue as the aircraft moves through the charged air. Lighting can be attracted to electrically charged aircraft. The charge build up can also interfere with air-band communications.
Lightning can literally blow the wing off a glider. The extremely high voltage, up to a billion volts, and as much as 200,000 amps, travel through the carbon fiber (conductive) structure and literally turn moisture to steam, which then blows the structure apart. Both pilot and student, in the example I'm quoting, were able to bail out and survived.
