Driving home from work from edinburgh to glasgow at around 15:30 sun is high in the sky. i'm in the back of the car my friend, his dad and his dads friend are also in the car. my friend is sleeping due to the distance we have to travel to and from work,his dad is driving and dads friend is in front passenger seat i'm behind front passenger.I was looking up at the sky as it was really warm(something we are not used to in scotland). i saw a black aeroplane which looked like a small kinda 1 or 2 seater crop duster type craft travelling in a straight line just below cloud line. after a few minutes of watching the aeroplane it was travelling towards a small cloud which was a little lower than the rest of the cloud line, the shape of the cloud was like a spinning top,the aeroplane went through the very bottom of the cloud and should have came straight out the other side but it did not which i found to be impossible, the sky was pretty much clear beyond where this happened as to why i found it weird, i'm not saying it was a ufo but it certainly made me question for about 20 mins afterwards where the plane had gone it was so weird it's like it just vanished behind cover of this small cloud. i'm 29 years old and have never seen anything like that in my whole life maybe you can shed some light on this thank you