US Army Europe (USAREUR) Practice Exam

The use of low-beam headlights is indeed required when visibility is substantially reduced by conditions such as fog, rain, or snowfall. Low-beam headlights are designed to illuminate the road directly in front of a vehicle without causing glare or reflection that can obscure a driver's vision in adverse weather conditions.

In fog and heavy precipitation, high-beam headlights can reflect off the moisture in the air, creating a wall of light that makes it even harder to see. Low beams, however, shine closer to the ground and provide adequate illumination without reflecting excessively off the precipitation. This is particularly important for ensuring both the driver's ability to see the road and the ability of other drivers to see the vehicle, which promotes safety on the road during such weather conditions.

The requirement to use low-beam headlights during reduced visibility is often reinforced in driving laws and regulations, highlighting the importance of using appropriate lighting during different weather scenarios to maintain safe driving practices.