Should you grit?
21st August, 2014
As you can imagine we always have one eye on the weather forecast, but at times predicting what Mother Nature is going to do can be an almost impossible task. With some weather patterns spanning just a couple of miles, conditions can vary drastically across a very small area. As if that wasn't complicated enough, even in a single location there are so many variables that influence whether we decide to grit, one of the most notable being the difference between air temperature and surface temperature.
Air Temperature: This is the temperature you will see on the weather forecast. The reading is taken at a fixed height, usually 1.5m above the ground, in a shaded enclosure known as a Stephenson Screen.
Surface Temperature: This is the temperature of the ground in a particular location.
During the day the ground absorbs solar heat, making the surface temperature higher than the air above it. As the day progresses and we move into the evening, the ground begins to lose the heat it has absorbed into space; cooling quickly and heating the air above it in the process. Depending on the weather conditions, and the time of year, the night time air temperature can be as much as five degrees higher than the surface temperature.
This means that, whilst the weather forecast may predict evening air temperatures of between 1 and 5 degrees during the winter, once you get down to surface level the temperature could in fact be at freezing point or below; causing a risk of ice. Having been trained by experts at the Met Office and with help from Weatherquest, our team have the skills and expertise to enable us to recognise the difference between these two temperatures. This helps us to avoid unnecessary gritting, whilst always ensuring that areas at risk of ice are protected.
Of course, if there is ever any doubt we will dispatch a team to carry out an inspection before making a decision.
Thanks to Jim Bacon from Weatherquest for his contribution to this blog.