When any object goes through the air, a thin cushion of air wraps around it that stays relatively still. This boundary layer is why you get dust trapped on your ceiling fan. At slower speeds, the air around a soccer ball moves smoothly over the surface and separates off the sides of the ball at its widest points. Imagine a ball moving from right to left across a clock, Goff explains, so traveling from the 3 to the 9. With laminar flow, the air flows over the surface and then flows off at the 12 and 6, which creates more drag in the air. Drag slows the ball down faster. At higher speeds, the air moves turbulently across the ball’s surface and peels off at the 2 and 4. The wind effectively wraps around the back. This turbulent flow has less drag, which means the ball keeps moving at high speed for longer.
“Had I seen the drag curve for Jabulani prior to the 2010 World Cup in South Africa I would have been calling FIFA and Adidas saying please don’t use this ball,” Goff says. The fact that the Jabulani became unpredictable and beach-ball-like during these long passes really helped Spain win in 2010, Goff says. The Spanish team relied almost entirely on short precise passes, without long kicks that became unstable with the Jabulani ball. “That was the perfect example of a team that really fit the style of play for that ball,” Goff says.
On the other hand, replicas (sometimes called training balls or gliders) are designed to be just like the official match balls but are much cheaper. Their panels are often stitched rather than thermally-bonded and are made of a different material. However, they’re not necessarily less durable than official match balls. So, they’re the recommended option for most players. https://www.youtube.com/watch?v=j2Xn84L3Kcs
×