Downspin??

Hi there. I'm a new member and I have recently seen a strange thing happen sometimes while hitting short irons...

Occasionally, I'll hit like a 8 iron and I will see the ball rise, then sort of abruptly jump downward, like it had some serious forward or downspin....?
Does anyone know what causes this??

Thanks......SD

Defective, damaged balls at low end driving ranges.

More then likely, the ball got a little out of round, either they came that way (low cost balls, any ball that has been hit hundreds of times.), or may have gotten a little dirt/mud on them making them out of balance. A golf ball is no different then an airplane wing, works with same aerodynamic forces, add/substract anyhting to the mix, like mud, cuts, dings, water and ball flight is severely affected.