The mass of water that, because of its transparency, looks dark in colour is called "black ice". Because it can be mistaken for the tarmac, it can make driving very difficult. Watch out!
January has got off to a strong start this year... as far as low temperatures are concerned. A couple of months ago we mentioned the subject of this article here, but without explaining what "black ice" actually is. Black ice on the road is proof that frost is highly dangerous because of its very appearance. How can we perceive a layer so thin that the road can be seen through it, as if it were transparent?
It is a phenomenon typical of mountain roads (with abundant vegetation) and high humidity. As for the times of day when it occurs most, these tend to be the first hours of the morning and the last hours of the evening. The cold, damp months of the year are ideal for black ice to form.
If we stick to what the World Meteorological Organization (WMO) says, black ice would be:
- A thin layer of ice on a body of fresh or salt water which, because of its transparency, appears dark in colour.
- The maritime term used when warning of a layer of ice which, because of its weight, can capsize a small vessel.
- The glaze of ice that covers rocks in the mountains, also known as verglas or glaze ice.
When falling rain combines with low temperatures, it may freeze on contact with the surface (in this case, the tarmac), especially if that surface is at 0 °C or below. Being transparent, this sleet is mistaken for the tarmac and is therefore imperceptible to the naked eye.
How to drive on black ice on the road?
Sticking to the first definition, which is the one that would affect us as road users on our journeys, it must be stressed that if the road is already damp and temperatures drop suddenly, there is a danger of a layer of black ice forming.
As it cannot be predicted, it is always advisable to:
- Drive very smoothly, in high gears and at low revs, turning before braking.
- Keep a safe distance, needless to say, avoiding any kind of skid, which can be fatal.
- Keep to a prudent speed, as this will allow us to detect one of the signs of this phenomenon, which is a certain shine on the stretch of road we are driving on.
- Fit winter tyres, which are advisable to improve grip.
- Activate stability control systems, if we have them, of course.