_RL  rq            ! rho * q for a layer

            rq =  rhos * qsnow

            rqh = rq * hs

               hs = hs - etop/rq

               rq =  rhoi * qicen(k)

               rqh = rq * hnew(k)

                  hnew(k) = hnew(k) - etop / rq

               rq =  rhoi * qicen(k)

               rqh = rq * hnew(k)

                  hnew(k) = hnew(k) - ebot / rq

            rq =  rhos * qsnow

            rqh = rq * hs

               hs = hs - ebot / rq

         rq =  rhoi * 0.5 _d 0*(qicen(1)+qicen(2))

         rqh = rq * hi + rs * hs