Aerosol size distributions derived from balloon-borne particle counter data from Laramie, WY, are used to calculate ratios of extincton, mass, and surface area to lidar backscatter at the widely used lidar wavelength of 532 nm. The results cover the range of the stratospheric aerosol layer from the tropopause to 30 km. These ratios may be used to infer particle extinction, mass, and surface area from midlatitude lidar backscatter data for the period late 1979 to 1993. This period includes the major volcanic eruptions of El Chich¿n and Pinatubo. The wavelength dependence of aerosol backscatter in the visible was calculated for the period 1991 to 1993 to allow conversions of the results to other lidar wavelengths. The wavelength dependence is similar to estimates from southern hemisphere midlatitude measurements indicating that these conversions may also be applied to southern hemisphere midlatitude lidar measurements. ¿ American Geophysical Union 1995