Low UFO sliding out of a cloud into clear blue sky.

Early morning drizzle stopped around noon, sky was clear blue with low white cloud rolls which were approximately 300 feet above the small hills of about the same height.  While driving south on PA State Route 51 a few miles south of downtown Pittsburgh just after noon a darker spot appeared in the end of one of these clouds seen at the top right of the windshield.  A quick look determined it was probably a puff of black smoke but another look was surprising to see a round saucer shapped craft slide out of the cloud into clear blue sky.  It was moving slowly from right to left bringing it closer but was tipped at about a 45 degree away.  Shortly after appearing in clear sky the craft went to a higher level about twice the height it had been at.  When it reached the higher level it still had the slow sideward motion and same degree of tip.  The motion to the higher lever was faster than the slow sideward movement but did not start out slow then get faster and slow down before stopping.  It was one smooth move and being tipped at that degree it carried the craft farther away and easily seen from the top of the windshield as it slowly crossed over the highway.  When it reached a point where it could be seen out of the driver's side window it suddenly came back down to about the same level it was when first seen.  The smooth fast motion back down was the same as when it went up and the tip never changed so it came closer.  When it stopped it still had the same slow sideward motion and it was observed sliding into the end of another cloud roll.  This craft never wavered and moved as if it was following a beam, when it went higher the craft maintained the same slant.  Assuming the visible part was the bottom of the craft no features,lights or sound was noted.  Judging by the height of the hills and clouds the size of this disc would be about the same as a small plane's wingspan.  Having recieved A's in Physics it was obvious this craft was moving with no propulsion system anyone had in 1965 an! d in fac t still do not today.