The flight instructor reported that the pilot was receiving landing training in his airplane. As the airplane touched down on the runway, a gust of wind caused it to balloon. The flight instructor ordered the pilot to go around, and the airplane accelerated to 85 kts in a slight climb. About 25 feet above the ground the airplane abruptly and rapidly pitched over to about 20° nose low. The flight instructor immediately came on the control yoke and pulled but received no response to his pull. The airplane impacted the runway about 10° nose low and slid off the left side into the grass where it came to a stop. The pilot, flight instructor, and a passenger egressed the airplane without incident. The airplane sustained substantial damage to both wings. The flight instructor reported there were no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation. At the time of the accident the airplane was landing on runway 27 with wind 290° at 14 kts gusting to 19 kts. The pilot reported that the nose dropped dramatically and that neither he nor the flight instructor had time to react with additional back pressure on the control yoke. The pilot said during the pitch over that his hands never left the control yoke. The flight instructor further reported that light clear air turbulence was present at the time and “windshear caused our demise.”