When is it necessary to use low beams while driving?

Using low beams in foggy conditions is essential because fog can cause light from high beams to reflect off the water droplets in the air, thereby reducing visibility instead of improving it. Low beams, on the other hand, direct light closer to the ground and create less glare, which is beneficial in fog, heavy rain, or snow. This helps maintain visibility of the road and any obstacles without causing excessive light scatter that might impair your vision.

In comparison, while low beams are typically used at night to illuminate the road ahead without blinding oncoming drivers, they are not exclusively necessary only during nighttime or in city driving unless other conditions warrant it, such as inclement weather. During the day, high beams can often be used when there is no oncoming traffic and visibility is good, making low beams less critical.