pro totpre, pres, w, nl, intppw, precip_h2o


precip_h2o=0.0
;
; Calculates the total precipitable water for a given
; radiosonde.

; Convert p from mb to Pa and w from kg/g to g/g
; Set up size of c.
;
	
	p=pres*100.

   w=w/1000.
   
	intppw=fltarr(nl)
	intppw(nl-1)=0.0
	for i=nl-1,1,-1 do begin
      dp=p(i)-p(i-1)
	   w_mean=0.5*(w(i)+w(i-1))
      precip_h2o = precip_h2o + w_mean*dp
      intppw(i-1)=precip_h2o/98.1
   endfor
  
;  Convert from kg m-2 to cm
	precip_h2o = precip_h2o/98.1
   
	end