Driving in fog feels like searching for your glasses in the pitch black.
Driving in fog feels like searching for your glasses in the pitch black. Vehicles, after all, seem to vanish into cloud and choosing a safe line can be extremely tricky. Furthermore, the nature of fog and the speed of traffic means that conditions can change quickly. Visibility can therefore be reduced from mid-range to poor within a surprisingly short time. Fortunately – according to the Highway Code – motorists can use front/rear fog lights when visibility is reduced to one-hundred metres. However, these must be switched-off when the conditions improve to avoid dazzling traffic and obscuring brake lights. Simon Elstow from The Institute of Advanced Motorists has further helpful advice:- “Before setting off, clean your windows and windscreen and ensure all your lights are working. - When you’re ready to leave switch on the dipped headlights. - Use your windscreen wipers on an intermittent setting to clear moisture. - Switch the heater or air conditioning on and leave it running to keep the inside of the glass clear. - Slow down and keep enough distance between yourself and the vehicle in front - make sure you can stop safely within the distance you can see clearly. - Fog is not the same density all the time – it may get thicker, slow down if it does. - Brake gently but earlier than usual so your brake lights warn drivers behind. - Be aware that other vehicles may be travelling without their lights on, so extra care and attention is needed. At junctions, wind the window down and listen for traffic. - Straining to see through thick fog will quickly make you tired – take regularbreaks. - Take high-viz clothing in case you have to leave the car.” Mr Elstow added: “Don’t underestimate the effect fog has on your visibility. Adjusting your driving to the weather conditions will help you to become a safer and more confident driver through the winter months.” The road safety expert concluded: “Fog is one of the most difficult conditions to drive in. Ensure you are prepared so that you can carry out your journey safely, and allow lots of extra time for the trip.” According to the Met Office, fog is caused by “tiny water droplets suspended in the air” and that “thickest fogs tend to occur in industrial areas” where there are numerous pollution particles on which water can form. Valley fog, in contrast, forms where “cold dense air settles into the lower parts of a valley” and condenses. Upslope fog, or hill fog, forms when winds blow air up a slope. The air cools as it rises which allows the moisture to condense. Furthermore, evaporation fog is caused by cold air passing over warmer water or moist land. This often leads to freezing fog that is composed of supercooled water droplets that remain liquid even though the temperature is below freezing-point. One of its characteristics is that rime (feathery ice crystals) can be “deposited on the windward side of vertical surfaces such as lamp posts, fence posts, and overhead wires”. Fog clearly makes driving more dangerous … so I would rather hunt for those glasses in the dark.