What is angle of attack in golf?

The vertical angle at which the clubhead approaches the ball at impact.

Angle of attack, defined

Angle of attack is the vertical direction the clubhead is travelling at the moment it strikes the ball. Positive means the club is moving upward, negative means downward. It is measured in degrees, and it is one of the few numbers in golf that genuinely changes what you should do with the rest of your setup.

The driver is the exception

The driver is the only club you are generally trying to strike on the way up. The ball is teed, so there is nothing to hit down into, and an upward strike lets you launch higher while spinning less, which is the efficient combination for carry.

Every other club is struck with a descending blow. The low point of the arc sits ahead of the ball, so the club meets the ball first and the ground second. That is what compression is, and it is what produces distance control and spin.

Why this dictates tee height

Once you accept that a driver wants a positive angle of attack and an iron wants a negative one, tee height stops being preference and becomes a consequence.

A driver is teed high because you want to catch the ball after the club has passed its low point and begun climbing, high on the face. An iron is teed very low or not at all because you want to catch it before the low point, while the club is still descending. Teeing an iron up moves the ball into a part of the arc where the club is still coming down steeply, which is why it produces high, weak, low-spinning shots.

What a hitting mat does to it

A mat is the worst surface for learning angle of attack, because it removes the feedback. On grass a club with too steep a descent takes a deep divot, and a club that bottoms out early takes turf before the ball. Both mistakes are visible on the ground. A mat does not break. The sole skids or bounces off the rubber, the ball travels a reasonable distance, and the error leaves no record.

That is why indoor practice can feel productive and transfer badly. The strike error a fairway would have punished is invisible on a mat, so it survives the winter intact.

Seeing it without a launch monitor

Watch the mat, not the ball. Where the sole marks the surface relative to where the ball sat tells you most of what a launch monitor would tell you about your low point. If the mark begins behind the ball position, you are bottoming out early, and no tee height will fix that.