how does Swing bowling and Reverse Swing bowling work in Cricket? Is it true that it is a fairly newer concept in the world of Cricket?

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how does Swing bowling and Reverse Swing bowling work in Cricket? Is it true that it is a fairly newer concept in the world of Cricket?

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A good question, and one that interested me as well, so I went looking. [According to Rabindra Mehta](https://www.espncricinfo.com/story/the-science-of-swing-bowling-258645), Nasa scientist and ex-fast club bowler, backed up by wind tunnel experiments, there are three factors: the speed of delivery, the angle of the seam† relative to the direction of flight, and the relative smoothness/roughness of the surfaces. But overall the principle is the same – the ball is delivered in a roughly static flight orientation such that the airflow over one side is smooth and laminar, whilst over the other side it’s rougher and more turbulent. The result is a pressure difference that exerts a sideways force away from the laminar flow. The ball’s seam leading at one side will produce turbulence behind it, so the ball will swing that way in flight; similarly, a ball that’s rougher on one side than the other will tend to swing towards the rough side (but not always – see below!).

What’s near-magic, though, is the effect that speed can have, which seems to have been a phenomenon he actually identified (or at least explained), that he terms “contrast bowling”. A ball that’s rough on one side and smooth on the other, delivered with the seam pointing straight ahead, at low pace, will swing one way. But the exact same ball delivered in the exact same orientation at high pace will swing the other.

Apparently the conventional wisdom is that swing bowling has been around since the beginning of last century, but Mehta points to evidence of bowlers like Grace having been aware of it prior to that. I’d suggest reading his article; there’s way more in it than I’ve summarised above.

†*For anyone who stumbles on this who knows nothing about cricket, I should explain that – unlike the cover of, say, a baseball or a tennis ball – the cover of a cricket ball is formed as two hemispheres, joined around the middle by a stitched circular seam. The position of the seam once the ball is released – during flight and when it bounces – can make a significant difference to the ball’s behaviour. Bowlers regularly hold the ball prior to release so as to deliver it with the seam in one orientation or another.*

Swing is created by angle of the seam as well as the ball having a shiny side and a rough side.

Normal swing is where the ball moves toward the rough side. Reverse swing moves toward the shiny side.

You might see a player rub the ball on their pants to shine it like an apple.

Reverse swing was pioneered by the Pakistani fast bowlers of the 70s.