What is radiation fog? Where is radiation fog in the UK today? Latest weather forecast
Dense fog will thicken throughout this afternoon into evening in Northern Ireland, Wales and the West of England, persisting into tomorrow morning causing further chaos for commuters and travellers.
The Met Office said: “Fog will persist in some parts of Northern Ireland during Thursday afternoon, thickening up towards dusk with the visibility falling below 100 metres in places.”
Thick fog has already engulfed much of England, Wales and Northern Ireland today with poor visibility causing travel chaos on the roads and potential flight disruption.
What is radiation fog?
Radiation fog occurs mainly in the winter, during clear skies and calm weather conditions.
On its website, the Met Office says: “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.”
Weather forecaster Mark Wilson says radiation fog is “not smog” and is a natural event.
He said: “It happens when you get clear skies and it cools down and you get fog patches forming out of these skies. The heat rises and then it cools down and that is why you get fog forming.”
Where is radiation fog in the UK?
The yellow weather warning for radiation fog today is effective in Northern Ireland, Wales and parts of England until 11am.
The warning covers Northern Ireland, Wales, north-west England, south-east England, West Midlands, Yorkshire and Humber and south-east England.
It is most prominent in areas where skies were clearest overnight. The map below shows the warning zones.
There are warnings that the “dense” conditions could cause travel disruption on roads with the possibility of some flights being cancelled or delayed.
Mr Wilson said: “There is a lot of radiation fog around at the moment. It is slowly lifting. There is some fog across East Anglia, southern and northern parts of England.
“The fog for most areas will lift later on and we will see some brightness in the west but in eastern parts it is going to stay quite cold today with some patches of rain.”
Rainfall will be concentrated in eastern parts of the UK, mainly in the far northeast and southeast parts of the country.
Temperatures are expected to remain low climbing no higher than 4C in the northwest but slightly warmer temperatures of 7C in London and the southeast.
Met Office meteorologist Aidan McGiven said: “The biggest issue will be the fog first thing Thursday, Northern Ireland, western parts of England and east Wales most at risk, there could be some issues on the roads, could be some flight delays because of the dense fog.”