You piped your drive down the fairway, but your ball picked up a clump of mud along the way -a common occurrence in soft conditions.
Barring a local rule that lets you lift and clean the ball, you’ll have to play it as it lies and deal with the dirt.
Traditionally, it’s been assumed that as the ball flies, the mud creates air resistance -or drag -that sends the shot in the direction of the ball’s soiled side. However this is not always the case.
Research completed by Keiser University in Florida (400 6 iron shots analysed by Trackman software) showed that a golf ball will curve to the opposite side of where the mud is located when the clump is small, but curve to the side of the clump when the clump is larger then the width of your thumb.
Here’s a cheat sheet:
- Large clump on left – ball goes left
- Large clump on right – ball goes right
- Small clump on left – ball goes right
- Small clump on right – ball goes left.
+The farther the mud is from the clubface/ball contact point, the more it will curve.
This is the short & sweet version, for more information you can find the the original article here.