Which factor usually leads to decreased visibility during high humidity conditions?

High humidity conditions can significantly impact visibility, and fog formation is a primary factor that leads to decreased visibility in such situations. When humidity levels are high, the amount of moisture in the air increases, which can lead to the condensation of water vapor, especially when temperatures drop. This process creates fog, which consists of tiny water droplets suspended in the air. When fog forms, these droplets scatter light, making it difficult to see through it, thereby reducing visibility.

Moreover, fog typically develops in conditions where high humidity occurs and is more pronounced in valleys or low-lying areas. This phenomenon is particularly common during early mornings or late evenings when temperatures cool down. While other factors like increased temperature and air turbulence can influence weather conditions, they do not directly lead to the formation of fog in the same way high humidity does. Additionally, altitude does not inherently cause visibility issues related to humidity; rather, it can be more related to other phenomena such as cloud cover or atmospheric pressure changes. Thus, fog formation directly ties into the effects of high humidity on visibility.