Fog is the accumulation of water droplets in the air, when water vapour has condensed back into a liquid – kind of like a cloud at ground level . Foggy weather significantly affects your vision of the road ahead, reducing the time you have to react to potential hazards on the road. Driving without due care and attention in fog could put you at risk of having an accident, which, at the very least, could lead to a claim on your car insurance.
There are three classifications of fog used by weather reporters, which give drivers an idea of the conditions on the roads:
Drivers who have to cope with difficult driving conditions regularly install driving lights on their vehicle, but you're unlikely to need them on UK roads. Driving lights are strong lamps that emit a focused white beam .
Unlike driving lights, fog lights have a wide, flat beam meant to illuminate the road and its surroundings ahead.
Daytime running lights are automatic headlights that turn on when the vehicle turns on. Newer cars often have daytime running lights installed over the standard headlights as they can make it easier for other drivers to see the car during the daytime.
Daytime running lights are too bright for night time usage, however, as they can dazzle other drivers, so they turn off automatically when headlights are turned on.
If you're struggling to find your car's fog lights, they may be labelled as something else.
Some models, such as a number of the Volkswagen Group's latest designs, have the equivalent of fog lights integrated into their headlamps and rear lamps.
Read your car manual to find what your vehicle has instead of fog lights, and then turn them on while parked to see how bright they are. They may be called 'all-weather lights' or something similar . If your manual doesn't have the information, ask at the car manufacturer's local dealership.
If your car definitely doesn't have fog lights, judge whether your head and rear lights will be strong enough in foggy conditions.
If your car is relatively new and has headlights that switch on as it gets darker, don't rely on them in foggy conditions. You should also switch them on when you go into darkness abruptly, such as when driving through tunnels.
Rule 235 of The Highway Code shares the following advice for drivers in fog: