On February 11, Texas witnessed a massive pileup involving more than 100 vehicles on the icy interstate. As winter storms blanketed the United States in snow, black ice led to freak accidents in many parts of the country. What is black ice?
Black ice is a very thin coat of transparent ice that forms on a surface, such as the road. The colour of the ice is not black, but because it is transparent and allows black top or asphalt on the road to be seen through, it appears black. The transparency of the ice is what makes it difficult to see, especially at night and on sunless winter mornings. There is, thus, a risk of slippage and subsequent accidents.
Black ice may appear wet and shiny, resulting in drivers mistaking it for a wet roadway. They may not recognise the slippery conditions, which increase the risk of accidents. And the sudden loss of traction experienced by vehicles under these conditions compounds the problem.
What causes black ice?
When there is a rise in temperature following a snowfall, snow on the ground would melt and cause road surfaces to become wet. If the temperature then drops while the ground is still wet, it will lead to formation of black ice on the surface due to refreezing. Black ice can also form when there is fog or rain in the same process as mentioned above. Moisture from vehicle exhaust can also cause black ice to form on roadways. Bridges and overpasses are prone to black ice because cold air flowing underneath the road surface contributes to lowering the pavement temperature. Shaded areas on the road are the other black ice-prone zones, as they receive less warmth from the sun during the day.
Picture Credit : Google
