to my knowledge a device known as a ROTATING BEAM CEILOMETER is used to determine cloud bases.
PIREPS made by intelligent, thoughtful pilots can be helpful...airliners will sometimes advise departure control...bases at X, tops at Y, higher above...before they go to center.
back in meteorological school....we could and did calculate the LEVEL OF FREE CONVECTION...useful in understanding CB/Tstorms etc.
if you are flying, you should certainly read: Weather flying by BUCK...buying the FIELD GUID TO CLOUDS might help too.
a useful tool while flying is any straight edge/ruler/checklist...look down the straight edge at the tops of the clouds, move your head back and look at the straight edge and see if it is pointed UP or down from level
pointed UP? you won't top the clouds at your present altitude
pointed down...you will clear at present altitude.
have fun