Frost can be deceptively dangerous. It can form on roadways, often unannounced, with the potential to snarl traffic and send vehicles skidding out of control at the slightest brake tap or acceleration. Drivers and pedestrians may have trouble spotting frost since it appears either translucent or white, making it a hidden hazard. Its infamously difficult-to-forecast nature only exacerbates the problem.
In warmer months, frost usually poses a threat only to plants. In the winter, frost can muck up the daily commute or halt it altogether. Driving can be extremely dangerous on frosty roadways. Stay alert to the signs and threat of frost to avoid succumbing to this deceptive winter hazard.
Types of Frost
Frost is the solid deposition of water vapour from humid air. It normally forms on still, clear, cold nights. The cool night air causes water vapour in the air to condense and form droplets on the ground. When the temperature of the ground or surface is below 0 degrees Celsius the moisture freezes into ice crystals.
The minimum air temperature is a good indication of the frost and ice risk in your area. However, in some situations a ground frost can form even when the air temperature is above 0 degrees Celsius. Frost will usually occur during clear winter nights when the sun’s absence causes surface temperatures to plunge. Cloud cover can act as a natural insulator, trapping warm air near the surface and hampering frost formation. Clear nights let heat radiate out into the atmosphere, cooling the surface and encouraging frost formation.
Still, many different factors contribute to frost forming—cloud cover, air temperature, wind speed and rainfall all influence the formation of frost, which makes it difficult to forecast more than a few days in advance. Depending on these factors and a host of others, frost typically appears in the following four forms:
- Ground frost forms on the ground or objects whose surfaces have a temperature below the freezing point of water. The ground can cool faster than the air and cause a ground frost without the air temperature dropping to 0 degrees Celsius. Grass will usually frost over before concrete or road surfaces, since grass cannot retain heat as efficiently.
- Air frost occurs when the air temperature falls to or below the freezing point of water. The air temperature must be at or below the freezing point of water at least 1 metre above the ground.
- Hoar frost is formed by the same process as dew, but when the object’s surface is below the freezing point. It can appear feathery when the object’s surface reaches the freezing point before dew begins to form on it
- Glaze and rime are not types of frost, but are often confused as such. Rime is a rough white ice deposit that forms when supercooled water droplets of fog freeze on contact with a surface as they drift past. Glaze forms when supercooled rain comes into contact with the ground, or when non-supercooled liquid comes into contact with the ground if the ground is well below 0 degrees Celsius. Glaze is clear ice that can be easily mistaken for a wet surface. It is highly dangerous.
Protect Your Property
Frost does not confine itself to just roadways or trees—it can quickly and secretly form on your property, damaging your building’s exterior, pipes and boiler. Frost can wriggle its way into your building through loose tiles, chipping paint, tiny cracks and exposed pipes. It can also freeze and burst pipes, causing a lengthy and messy clean-up process. Protect your property by heeding these general precautions:
- Service your boiler and insulate your pipes. Because frost can burst pipes, make sure your boiler is working properly and your pipes are insulated against the cold. If your pipes burst, you could be without heating and hot water. Stay up to date on boiler maintenance and pipe insulation to ensure your building stays warm.
- Locate your main stopcock and learn how to turn it on and off. Without knowing where and how to operate the main valve regulating water flow into your building, you may be unable to clear your pipes and thus prevent them from freezing.
- Inspect all insulation. All pipes and tanks in loft spaces or anywhere liable to freeze should be inspected and insulated properly.
- Clear all gutters. When your gutters are blocked, water overflows and runs down your outside wall. That excess water and any frost that forms on your building’s exterior can work their way through tiny cracks in porous brick and cause serious damage. Clear your gutters to prevent overflow and any damage.
- Examine your building’s exterior. If frost gets into loose paintwork, cracks or open joints, it can take hold and cause damage from the inside, invading your property with water and cold weather damage.
- Survey your roof. Your roof should be watertight with no cracked or missing tiles. Even the smallest hole can provide frost with an opportunity to enter and wrench apart tiles by freezing and refreezing.
- Allow heat to circulate. Heat should circulate through your whole building to ensure colder areas that contain pipes do not freeze. Keep inside doors open to encourage heat circulation.
- Leave heating on at least one hour each day. Neglecting to heat your building, even if you are away, can lead to freezing pipes, which can burst and cause a huge hassle.
- Let a slow trickle of water flow through taps connected to pipes that run through colder spaces. Either drain the water system or let water flow at a slow trickle to discourage freezing from frost.
- Cover plants during frosty evenings. Use simple, fleece-covered frames or a layer of straw sandwiched between two sections of chicken wire to cover and insulate outdoor plants against frost.
Driving in Frost
When frost forms on roadways, driving can be treacherous. Making things more dangerous is the fact that most UK motorists do not know how to drive in frosty conditions. Follow the tips listed below to ensure your safety when driving on frost-covered roads.
- Clear all vehicle windows of snow and ice using a scraper and de-icer.
- Stay vigilant when clearing snow from your running vehicle—leaving it unattended even for a moment while it warms up extends an open invitation for thieves to ‘frost jack’ your vehicle.
- Use a lighter to warm your key for a frozen lock rather than breathing on it, which produces condensation which then freezes.
- Ensure your tyres are appropriately inflated—full tyres provide better traction and control.
- Travel with a full tank of fuel for extra vehicle weight and increased traction.
- Stop 10 times sooner than you would on normal roads.
- Clean your number plates.
- Steer and brake gradually to discourage skidding.
- Stay calm if your vehicle skids—simply lay off the accelerator and gently steer in the desired direction rather than relying on the brakes.
- Obey the speed limit.
- Accelerate only on straight stretches—accelerating when entering a bend may force your vehicle to spin.
- Carry a mobile phone with you at all times in case of emergencies.
Stay safe when severe weather strikes by being prepared and checking weather forecasts and warnings.