The hemispherical structure was creased with "longitude lines" running from the pole to the equator. In another minute the equatorial region had partially caught up with the poles giving a flattened out appearance to the top of the structure. In the next few minutes the symmetry of the structure was broken up by wind currents at various altitudes so the shape of the cloud cannot be described in any geometrical manner. In about 8 minutes the top of the cloud was at approximately 40,000 feet as close as I could estimate from our altitude of 24,000 feet and this seemed to be the maximum altitude attained by the cloud. I did not feel the shock wave hit the plane but the pilot felt the reaction on the rudder through the rudder pedals. Some of the other passengers in the plane noted a rather small shock at the time but it was not apparent to me.
