The NASA/Goddard Space Flight Center Scanning Raman Lidar has made measurements of water vapor and aerosols for almost ten years. Calibration of the water vapor data has typically been performed by comparison with another water vapor sensor such as radiosondes. We present a new method for water vapor calibration using pressure and temperature data at cloud base. With ground P & T measurements, the cloud base algorithm agrees with the radiosonde moisture calibration to within 7%. With radiosonde pressure and temperature measurements at cloud base from radiosondes that went through a cloud, the cloud base algorithm agrees to within 1% of the radiosonde moisture calibration. Analysis of water vapor and aerosol measurements made in the vicinity of Hurricane Bonnie are also discussed.