How does relative humidity affect the way water droplets contact a surface?

Droplet impacts on a solid surface play an important role in many natural and industrial processes, including ink-jet printing, anti-icing, and spray coating. In this study, we set up several experiments focusing on the effect of relative humidity on drop contact dynamics. We began with building a chamber in which we could manipulate the relative humidity by introducing either dry or moist air and aligning the chamber with a novel optical imaging setup containing environmental controls. We completed two sets of experiments, one in which the relative humidity inside the chamber was approximately 5% (low humidity) and one in which it was close to 95% (high humidity). At each of these humidity levels, we completed a series of trials in which we changed the Weber number of the water droplet. The completed experiments show that the lifetime of the droplet is shorter at high humidity in comparison to low humidity. Based on the results of our experiments, we see that relative humidity plays an important role in drop contact dynamics which will apply to many industrial and biological processes.