AN UNUSUAL DISPLAY OF NOCTILUCENT CLOUDS

On the morning of July 1, 1990, an intense display of noctilucent clouds as seen from Namao, Alberta, completely disappeared in 30 min. Observations of the clouds from Slave Lake, Alberta, indicate that the display lasted only slightly longer from that site. The noctilucent clouds' rapid degeneration may have been due to induced heating of their formation zone, perhaps by a coincident aurora.