ABSTRACT
The second general type of rainfall simulators uses spray nozzles to produce raindrops. Early nozzles, such as those used for watering gardens tended to produce large drops, high intensities, and low impact energies. Over time, these nozzles have been replaced by ones that produce drop size distributions, more similar to those of natural storms, at pressures that produce near terminal impact velocities. However, most of these nozzles produce intensities well above those found in natural storms of interest. To overcome these high intensities, intermittent rainfall is produced by intercepting a portion of the water before it strikes the soil surface. Mechanical systems for rainfall interception have been replaced by computer-controlled systems that make it possible to produce storms with varying intensity patterns.
