How does 100% humidity affect bullet trajectory at a distance of 600 meters?

High humidity can have a significant impact on bullet trajectory. At 100% humidity, the air becomes denser with water vapor. This increased humidity can cause a bullet's trajectory to rise slightly due to the reduced density of dry air that typically provides less lift.

As humidity increases, the lighter water vapor replaces some of the heavier nitrogen and oxygen molecules in the air, which can result in a phenomenon where the bullet experiences a slight upward shift in its path. This is particularly evident at longer distances, such as 600 meters, where even small environmental factors can significantly influence the bullet's path.

In practical terms, this effect might lead to an impact that moves up about 1/2 inch when considering a trajectory at that distance. Thus, the correct interpretation of the effect of 100% humidity on bullet trajectory aligns with the assertion that it moves the impact up by approximately 1/2 inch.