The sole purpose of fog lights fitted to a car is to 'provide a powerful and concentrated beam of light that can penetrate fog and heavy rain and which will make your car visible to other motorists', as explained on the powerbulbs blog.
While full beam or brights will reflect light back off fog, fog lights are able to sneak light under mist. A fog light is usually located beneath a headlight and is fitted with a wider, flatter beam.
You may wonder why have I decided to begin my column with that explanation? The reason is I've come across many motorists who reckon fog lights shouldn't be used in adverse weather conditions, but rather during perfectly good weather conditions.
In South Africa, there's no mandatory requirement for cars to be fitted with fog lights in the front or rear. However, I've noticed many motorists whose vehicles do have them fitted (either as standard or aftermarket) simply don't use them at the correct time.
In Europe, motorists are not required to have cars fitted with rear fog lights and in the United States, motorists are allowed to have rear fog lights but they're not mandatory.
The diagram by the PIAA Corporation below illustrates how different light systems work:
Used at the wrong time
I've seen motorists driving at dusk and even at night without their headlights. Instead, they use their 'park' lights and a set of front fog (or spotlights) to (badly) illuminate the road ahead but also make themselves visible to other motorists and pedestrians.
And then some people think it's a good idea to turn their rear fog lights on at night sans fog or heavy rain. I mean, come on? Is it to show off that your car has fog lights or do you simply not know what they're used for?
It's a matter of road safety that we learn the basics of what certain functions on the motor vehicles we drive are for.
Let's get better at driving on our roads, and educating motorists that by using fog lights during situations is wrong. The image below shows a conventional light switch fitted to a car and the logos on the top are the most important.
Moving in a clockwise direction: the circle signifies off, the next icon are the park lights, the following setting is the full headlights and the fourth is when the car automatically switches on the headlights.
The two icons on the left hand side are for the fog lights, the top is the front and below is the rear.
Image: Jeff Siepman