Icebound's post is well-written and almost exactly accurate. Just one
quibble:

Icebound wrote:

"dry adiabatic" mean no heat
added and no condensation occurring. This number has been
experimentally determined... it is an almost straight line
value of approximately 3 degrees C per 1000 feet.

The dry adiabatic lapse rate is not an experimentally determined
number. It can be derived from equations, and turns out to be defined
by the remarkably simple expression: g/Cp, where g is gravity (9.8 m/s)
and Cp is the specific heat of dry air (1004 J/kg). Perhaps the
experimental nature you're referring to has to do with an "average"
moisture content which acts to change Cp slightly?

Jim Rosinski