What is the effect of fog lights?

[IslaFitz]

Fog lights are installed at the front of the car, slightly lower than the headlights, and are used to illuminate the road during rainy or foggy weather. In foggy conditions with low visibility, the driver's line of sight is limited. Yellow fog lights have strong light penetration, which can improve the visibility of both the driver and surrounding traffic participants, ensuring driving safety. Here are some precautions regarding the use of fog lights: 1. Fog lights are suitable for severe weather conditions such as heavy rain, fog, snow, or dusty environments. The visible range of fog lights is approximately 100 meters. When visibility drops below 100 meters, it is necessary to turn on the fog lights and reduce speed. 2. When visibility is below 30 meters, the effectiveness of front fog lights is limited, and it is advisable to pull over and turn on the hazard warning lights. 3. In rainy, foggy, snowy, or dusty weather, besides turning on fog lights and reducing speed, some drivers may habitually turn on the hazard warning lights (double flashing lights). However, this is unnecessary. Firstly, fog lights have much greater penetration than hazard warning lights. Secondly, when hazard warning lights are turned on, the vehicle loses the ability to signal turns, making it difficult for drivers to indicate turns or lane changes, which can easily be overlooked by other vehicles and lead to traffic accidents.

[DeBrayden]

I have fog lights installed on my car, and the most noticeable feature is their strong penetration in rainy and foggy weather. Regular headlights reflect a blinding white haze in thick fog, but the slightly yellowish light of fog lights can cut through the moisture, providing much clearer road illumination. The rear fog light functions more like a hazard warning light—it should be turned on when visibility drops below 50 meters during heavy rain, acting like a conspicuous red warning sign at the rear of the car, making the car's outline noticeable to vehicles far behind. However, it's important to note that fog lights are glaring and unsuitable for daily use. In some European countries, cars are required to have anti-glare rearview mirrors when fog lights are mandatory, though this regulation doesn’t exist in China.

[SanAndres]

After upgrading the fog lights myself, I found them truly practical in two scenarios: during rain or snow when road surface diffuse reflection is severe, the fog lights provide close-range fill light to clearly see lane markings; and on mountainous winding roads with fog, where regular LED headlights seem to hit a wall, halogen fog lights can actually illuminate the edges of curves. There are now yellow LED fog light kits available as aftermarket parts, but real-world testing shows that classic halogen bulbs still offer better penetration. The design of the reflector with metal mesh is also crucial for controlling the light angle.

[StArabella]

Fog lights are designed with low color temperature for better penetration. The yellow light with a wavelength of about 3000K scatters less in rain and fog, making it more effective than the 6000K white light of headlights. Front fog lights are typically installed on the front bumper at a low position to avoid creating a light curtain in fog. Rear fog lights are required by regulations to be at least three times brighter than taillights and can also serve as supplementary brake lights in emergencies. However, it's important to note that retrofitting fog lights with strobe modes is illegal.

[VonHaley]

Last month's mountain road drive in a torrential downpour taught me the true value of fog lights. With windshield wipers at maximum speed still struggling and preceding vehicles kicking up blinding water spray, hazard lights only added to the visual chaos. The moment I switched to fog lights, I could suddenly discern the roadside curb stones! Those warm yellow beams with ground-guidance effect, combined with lowered headlight angle, boosted safety perception exponentially. Later research revealed EU-certified fog lights must provide 40 meters of clearly defined illumination.

[VonMax]

From a safety design perspective, fog lights are essentially environmental compensation lights. Front fog lights require a 15-degree wide-angle scatter to avoid glare from fog; rear fog lights are mandated to be installed on one side only to prevent confusion with brake lights. Germany also stipulates that fog light circuits must be directly connected to the ignition switch to prevent battery drain from being left on. An interesting tidbit: some luxury vehicles intelligently supplement lighting with fog lights when turning, a feature that works by linking with the steering sensor.