Answer:
Water droplets slowly forming until they reach a size that can no longer be suspended in the air.
Explanation:
When air becomes saturated with whater, it can no longer maintain water as a gas. Some water molecule come together and stay that way. They, in turn, coallesce with other nearby particles. This continues until the droplets are large enough that they begin to noticeably refract the sunlight, producting the visual effect we call clouds. The droplets are suspended in air - an heterogenous suspension called a colloid. At some point the colloid cloud begins to shed the larger water droplets, usually directly over my spot on the trail.
