Final answer:
The most important precipitation process in producing rain from a nimbostratus cloud containing ice crystals and cloud droplets of all about the same size is supercooling and ice crystal formation.
Step-by-step explanation:
The most important precipitation process in producing rain from a nimbostratus cloud containing ice crystals and cloud droplets of all about the same size is the process of supercooling and ice crystal formation.
In this process, the small droplets of water in the cloud remain as a supercooled liquid down to about -10°C, rather than freezing into ice crystals that are more suitable nuclei for raindrop formation. To induce rain, small granules of solid CO₂ (dry ice) can be dispersed into the cloud from an airplane. As the CO₂ sublimes, it cools the water droplets, causing them to crystallize and provide nuclei around which raindrops can grow.
Therefore, the supercooling and ice crystal formation process is the most important in producing rain from a nimbostratus cloud with ice crystals and cloud droplets of all about the same size.