On the Practical Determination of Height from Upper-air Data

Shaw, Keefer, Refsdsl and others (1) have shown that goopotential height is represented on the tcphigrani by an area, and that an isentropic at'mosphere XY (figure l), equal in geopotential height to a given atmosphe,re AB, may be const8ruct8ed by so placing the line XY on the tepliigram t,hat the area XAZ is equal to the area YBZ. The effect of moistmure is normally negligible, but may be allowed for, if desired, by substituting virtual temperat,ure for actuol temperature in drawing the curve of state AB. In an isentropic atmosphere the lapse rate is approximately constant a.nd equal to 9.86" C. er kilometer (2) or