What it measures
Landing angle, sometimes called land angle or descent angle, is the angle between the ball's path and level ground as it comes back down to the height it was launched from. It is measured in degrees. A higher number means a steeper fall.
It has no left or right sign. It is measured at launch level, so it describes the shot as if the ground were flat, regardless of whether the real target sits above or below you.
Typical numbers
PGA Tour averages put driver landing angle at about 38 to 39 degrees, a 7 iron at about 50 degrees and a pitching wedge at about 52 degrees. LPGA Tour players tend to land a few degrees shallower because their shots fly lower.
Everyday golfers usually land the ball flatter, often around 30 to 35 degrees with driver and 38 to 45 degrees with mid irons. Roughly 40 to 45 degrees is generally the point where irons start holding greens well, though that varies with green firmness.
What changes it
Landing angle follows height. Anything that makes the ball climb higher, such as more ball speed, more launch or more backspin, tends to steepen the descent. Low-spin, low-launch shots come down flatter.
Wind matters too. Into the wind the ball climbs and drops more steeply. Downwind it flattens out. In the swing, delivering a bit more dynamic loft or creating more spin loft will usually steepen landing, while heavy shaft lean and low spin flatten it.
What it changes
Landing angle is one of the biggest factors in roll. A steep landing spends most of the ball's energy on the ground at impact, so it stops quickly. A shallow landing keeps more forward speed and bounces and rolls. That is why landing angle, together with spin, drives the gap between Carry and Total.
For approach shots, a steep landing matters at least as much as spin. A ball landing flat with plenty of spin can still skip through a firm green. For driver, a moderately shallow landing adds useful run out.
How to use it
Use different targets for different clubs. With driver, aim for a landing angle in the mid to high 30s with good carry. With irons, check that your mid and short irons land in the 40s or steeper. If your long irons land much flatter than that, a hybrid or higher-lofted option may hold greens better.
Bay drill: hit five shots each with your 5 iron, 7 iron and 9 iron and note landing angle. Any club below about 40 degrees is one that will struggle to stop on firm greens. Then try to add a few degrees to that club with a slightly higher finish and full release, while watching carry.