What is launch angle in golf?

The vertical angle at which the ball leaves the club face at impact.

Launch angle, defined

Launch angle is the vertical angle (in degrees) at which the golf ball departs the club face at impact. PGA Tour driver averages cluster near 10.4 degrees.

Why it matters

Carry distance is a function of launch angle, ball speed, and spin rate. For driver, the sweet spot is 10-14 degrees launch with 2,200-2,800 RPM spin.

How tee height changes launch angle

For a driver, every quarter inch of additional tee height raises launch angle by roughly 1 degree (and lowers spin by ~200 RPM).