The effects of temperature and surfactant on secondary droplets produced by the impact of raindrops on water surface were experimentally studied in a rain facility that consists of a rain generator and a deep water pool. The rain generator is a 0.9 m × 0.6 m rectangular tank with 360 hypodermic needles mounted on its bottom. A constant water height is maintained in the tank to obtain a constant dripping rate of raindrops from the needles. The rain generator is placed 2.2 meters above the water pool that is 1.22 m long by 1.22 m wide with a water depth of 0.31 m. A circular motion of the rain generator varies the impact locations of the raindrops on the water surface.Both the raindrops and secondary droplets are measured with an in-line holographic technique that employs a collimated laser beam and a high-speed camera. The diameters and two-dimensional positions of the raindrops and secondary droplets were first reconstructed in each holographic image using a GPU-based holographic reconstruction algorithm. Then an in-house particle tracking code was implemented to compute their diameters, trajectories and instantaneous velocities. The measurement data shown in this thesis was taken at 9.5 cm above the water surface of the pool. In this study, the effects of temperature and surface tension on the production of the secondary droplets were examined separately. When studying the temperature effect, the temperature of the water in the rain generator varied from 7 degrees Celsius to 20 degrees Celsius (room temperature) while the water temperature in the pool was maintained at room temperature. When studying the surface tension effect, certain amounts of soluble surfactant (Triton X-100) was added into the water pool to vary the surface tension from 40 mN/m to 73 mN/m, while the rain water is kept clean with a surface tension of 73 mN/m. It is found that both the rain temperature and the surface tension of the water pool have an impact on the production of secondary droplets. The temperature of the rain could change the viscosity by more than 40%, therefore resulting in a significant difference in the number and the size distribution of the production of secondary droplets. On the other hand, while the surface tension of the water pool does not heavily influence the number of secondary droplets, it does contribute to a difference in size distributions of these droplets at around R = 120 μm.