The flight instructor reported that, during approach at a low level, due to "wind shear" the airplane had a sudden altitude loss. The pilot increased the engine power to full but the tailwheel equipped airplane touched down "harder than normal." The airplane impacted the airstrip with a side load; the left wing and left landing gear separated. The airplane slid to a stop and came to rest upright. The airplane sustained substantial damage to the left wing. The instructor pilot did not report any mechanical malfunctions or failures with the airplane that would have precluded normal operation. According to the instructor, "wind shear conditions" were present on the approach. The pilot reported the wind from 180 degrees, light and variable at 7 to 10 knots. The automated weather observation station located on the airport about 8 nautical miles away reported that the wind was from 200° at 9 knots; visibility at 10 SM; cloud condition few at 11,000 ft. AGL; temperature 61°F; dew point 39°F; and barometric setting of 29.80 inches Hg.