Cloud drifting across Britain could take 36 hours to clear

The ash could also affect Scandinavian countries as well as,

eventually, France and southern Europe, weather forecasters said yesterday.

The UK is going to be affected as winds at the moment are from the north, switching to north westerly.

Brendan Jones, a forecaster with MeteoGroup, the weather arm of the Press Association, said: "At present the Icelandic eruption is not a big one, although we have to wait to see if there are further eruptions.

"The ash that will come over the UK will not be a huge plume but will be diffused and will feature small ash particles."

He went on: "It will be difficult to detect and the only visible sign could be lurid sunsets that often are a feature after an eruption.

"Ash particles from eruptions can spread widely which is why Sweden and Norway could get ash. The ash at present is moving south east from Iceland and will probably be clear of the UK within 24 to 36 hours as long as there are no further disruptions."

The concern is that the eruption of Eyjafjallajokull, which has sent the cloud of ash into the sky, is the first in nearly 200 years and geophysicists fear it could trigger a much larger explosion of nearby Mount Katla.

Katla is described as "enormously powerful" and because it lies under a glacier its eruption would cause a huge glacial outburst flood and could spread its shadow over a much larger area.

Over the years, volcanic eruptions have had a huge effect on the weather.

The moon "turned blue" after the massive 1883 eruption of Krakatoa in Indonesia.

In 1815 a huge eruption on the Indonesian island of Sumbawa caused freak weather conditions throughout the world.

Mount Tambora spewed out massive amounts of sulphur dioxide which combined with water vapour to form a sulphuric acid mist that reflected sunlight away from the earth.

That caused such a drop in temperatures that 1816 became known as "the year with no summer".

Crops failed owing to low daytime temperatures, late frosts and abnormally high rainfall, provoking food riots, famine and disease.

In Ireland rain fell on 142 days that summer and across France the grape harvest was virtually non-existent.

In North America there was snow in June and lakes and rivers froze as far south as Pennsylvania during July and August.

It followed a smaller eruption in Iceland just over 30 years earlier that caused a thick fog of gas virtually wiping out the summer of 1783 across much of Europe and North America.

Passengers asked to wait

Airports across the UK are asking passengers not to travel because they expect services to resume and to wait for an announcement to be made. They should instead contact airlines direct for information about their options.

Some operators, including Jet2 at Leeds Bradford Airport, are already working to add additional flights to schedules over the coming days. Information can be obtained from the airlines.

Those looking to use ferry services instead should contact individual operators direct.