Thick fog will last well into Tuesday morning

Fog warning: travel may be impacted by poor visibility

The Met Office has issued a new yellow warning of fog for Greater Manchester through to 12:00 noon on Tuesday.

Thick fog will last well into Tuesday morning hence drivers are advised to slow down, keep their distance from the vehicle in front and use the correct lights.

The Met Office warns: 'Some minor disruption to travel is likely with poor visibility leading to difficult driving conditions on some roads.'

Driving in fog

Motoring organisation the AA advises:

• According to the Highway Code, you must use headlights when visibility is seriously reduced - generally when you cannot see for more than 100m (328ft), or the length of a football pitch
• There's no obligation to use fog lights but if your car is involved in an accident and they weren't on, then your insurer may ask questions
• Generally it's better to be safe than sorry, so use fog lights when appropriate, but don't keep switching them on and off - this can be a distraction to other drivers so wait for a consistent improvement in visibility before turning them off
• Be able to stop within the distance you can see clearly

Thick fog

Several factors have combined to make the fog particularly thick.

The ground is moist due to lots of rain last week and warm daytime temperatures means the air can hold more moisture, so there is more to condense at night.

A high pressure system over Britain has brought clear skies, making for cold nights and very little wind to disperse the fog.

Radiation fog

There are a number of different types of fog; the fog we are currently experiencing is radiation fog.

Radiation fog usually occurs in the winter, aided by clear skies and calm conditions. The cooling of land overnight by thermal radiation cools the air close to the surface. This reduces the ability of the air to hold moisture, allowing condensation and fog to occur.

Radiation fogs usually dissipate soon after sunrise as the ground warms. An exception to this can be in high elevation areas where the sun has little influence in heating the surface. Also thick fog can block much of the warming, causing it to hang around until noon or longer.

http://www.metoffice.gov.uk/learning/fog