What are fog lights, and when should you use them?

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What are fog lights, and when should you use them?

South African motorists seem to have a love affair with their fog lights.  Whether the car they drive is old or new, you’ll notice a large majority of them permanently have their fog lights on, even in broad daylight.  But what are fog lights supposed to do?  How do they work?  Most importantly, when is the correct time to use them?  I assure you, it’s not during bright sunshine.

What are fog lights?

Fog lights are, as their name suggests, lights to be used during foggy situations, and alternatively during rain, snow, smoke, sandstorms, or other low light, low visibility circumstances.  Front fog lights are low-positioned lamps that generally provide a low, wide beam of light, typically white in colour, although European-spec cars and bikes sometimes have a yellow or orange tint.  Rear fog lights, are brightly-lit red lights positioned often within the taillight clusters of a car.

How do fog lights work?

Fog lights are designed to increase visibility during low-visibility weather such as fog, rain, snow, smoke, or sandstorms during low-light situations.

When we drive though any of the conditions mentioned above at night, our 1st instinct is to switch from regular low beam headlights to high beams, or ‘brights’ as they are commonly referred to.  By doing so, the bright light is aimed higher, and reflects directly back at the driver, obscuring vision and creating a blanket-like effect preventing one from seeing much farther than a meter or two in front of them.  This is the wrong thing to do in the situation and could result in an accident as the driver is unable to see the road and traffic ahead of him/her.

Low beams, high beams, and fog lights illuminate the environment in different ways, be sure to use the correct lights for the correct situations
Low beams, high beams, and fog lights illuminate the environment in different ways, be sure to use the correct lights for the correct situations

Front fog-lights are placed low to prevent their light reflecting off the water/dust particles and obscuring the drivers view.  Hence they give the impression of providing light under the fog/rain/snow/sand.  The height of the lights relative to the ground is un-important, as the only relative difference in height that matters is that between the eye-level of the driver, and the directional height of the fog lights.

The beam of the fog lights is aimed much closer to the vehicle than the standard low beams of a car – again to prevent light reflecting and obscuring the driver’s vision.  This beam is low and wide, providing greater visibility of a wider angle of vision, allowing the driver to see the edge of the road clearly in inclement weather.

Rear fog lights have the simple task of shining bright enough that other drivers are able to see that there is a vehicle ahead of them.  As a result of this intention, these lights are as bright as the brake lights of modern vehicles.

Fog light diagram 1

 

When is the correct time to use fog lights?

In South Africa, fog lights get used all the time; but when is the appropriate time to use them?

Front fog lights have a dedicated function that can be used in a broad range of situations.  Although they are named fog lights, they can be used whenever visibility is low.  For example, front fog lights can be used in heavy rain, snow, fog, sandstorms, and when driving through smoke.  Front fog lights should not be used merely as a ‘fashion statement’ – as they often are – and they serve absolutely no purpose during the day.  However, as they are aimed low, they can be used at night without negatively influencing other road users.

As this beam is not as far-reaching as standard low-beams, when using fog lights during low-visibility situations, one should drive much slower – the standard response for low-visibility scenarios.  In extremely foggy weather, it is often advisable to turn the front headlights off altogether and rely solely on the fog lights, as there will be minimal interference with the driver’s vision.

Rear fog lights can often be operated independently of the front fog lights.  These should only ever be used in low visibility, low light scenarios.  As these lights are incredibly bright, they are easily confused with brake lights, causing other drivers on the road to respond as such.  At dusk, these lights also create a large amount of glare, obscuring the visibility of drivers behind you.  As such it is highly important that the rear fog lights only be used during fog, smoke, snow, or similar situations.  These lights, when used incorrectly can be temporarily blinding for other drivers; as such they must be used appropriately.

 

How do I know if my fog lights are on or not?

Many drivers are often unaware that they may be driving with their fog lights on.  To see if you are, when the car is on, there will be illuminated icons on the instrument cluster to inform you if the fogs are in use:

If one of these symbols is illuminated on your dash, you're driving with your fog lights on.
If one of these symbols is illuminated on your dash, you’re driving with your fog lights on.

Conclusion:

Fog lights provide additional safety and visibility during bad weather and low-visibility scenarios.  The correct usage of these lights may not only save your life and those using the road with you, but will also make you a much more pleasant person to share the road with.

It is important to note that regardless of how great new headlight technology is, a standard headlight configuration will never provide the same level of visibility as fog lights will under the appropriate circumstances.

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