Since the reduction of burning fossil fuels in the UK during the latter part of the 20th Century, extensive fog has been something of a rarity in the UK. Occasional fogs do come and go, but the seemingly endless fogs of the 1950s, which lasted for days and days on end, seemed a thing of the past. However, during the third week of December 2006, the synoptic pattern would come together to give some of the most extensive fog seen for years. Amongst much travel disruption, the UK's largest airport, Heathrow, was effectively closed for days, creating havoc for those on the Christmas getaway.

Please visit page 5 of our video section for timelapse footage of this fog event.

A huge area of high pressure developed over the UK during the 18th December, and that remained the UK's most dominant feature right through to the early hours of 23rd December. Below is the synoptic chart from the UK Met Office, which shows the high's position at midnight on the 19th December, thanks to Wetterzentrale:

Below is another synoptic chart showing the positioning of the high, this time at midnight on the 22nd December:

Below is a satellite image showing fog at around midday on the 20th December. On this particular day, the fog was quite patchy, but across Weybridge (our home village) the fog hung around all day. Note how the fog is butting up against the South Downs on this image, the ridge of high ground just inland from the south coast of England. This image is provided by the MODIS rapid response satellite website.

By the 21st December, Weybridge was into its third consecutive day of fog, which had not cleared since the evening of the 18th. It was during this day that the EOTS team decided to head to the high ground of the South Downs in Hampshire and West Sussex. The aim was to climb above the fog, actually enjoy some sunshine, and capture some of the fluid motions of the tops of the blanket of fog.

Below the fog, heading through the valleys between the South Downs, scenes were common but grim. The fog limited visibility to 100m at times, and as the hedgerows to the left of this image show, the fog was dropping rime ice in places.

We headed onto Butser Hill in Hampshire, one of the highest peaks along the South Downs. Here, we broke into the sunny skies, and watched fog cascading over the tops of lower hills to our east, into the valley below.

As a large amplitude fog wave rose out of the valleys below, it had enough energy and momentum to roar over the tops of the Downs, oozing across the fields.

As each wave of fog rolled over the tops of the Downs, it left supercooled droplets clinging to vegetation in the form of rime ice. This is quite rare in the UK too.

By standing on a ridge with the sun behind us, we were able to cast a shadow onto the banks of fog in the valleys below. Around our shadow, a Brocken Spectre appeared, visible as concentric rings of colour around the viewer's head.

Back into the fog, and on high ground near to the fog tops, rime icing and more general icing was quite stunning. Here, trees are heavy with a coating of solid ice.

A mixutre of rime ice and solid ice, clinging to trees on the Downs.

Nothing was safe from the blowing fog, and thus nothing was safe from the deposition of rime ice. The rime built up in the direction of the fog-flow.

Another great example of the riming of just about everything the fog touched!

We moved eastwards to the Trundle, another high peak along the ridge of the South Downs, north of Chichester. Here, fog remains thick in the valley below, but above, a layer of stratocumulus moved in from the east.

The same view a short time later, showing how the advancing cloud was forcing the low-level fog to collapse as the air was warmed by the cloud blanket.

It was pretty chilly on top of the Trundle, with fog occasionally breaking over the top!

Another impressive Brocken Spectre, viewed from the Trundle.

A 180 degree panoramic shot of the fog below,
viewed from west, through north, to east.

As witnessed in north Wales back in 2005, fog rollers were happily gliding past.

A couple of brave souls watching the fog below at sunset.

The final shot on the 21st, with fog re-gathering down below at sunset.

On 22nd December, day four of the fog, we headed to the fog's southermost edge, which was dammed up by the Hog's Back. This is a narrow ridge which runs west to east through Hampshire and south-west Surrey. The fog was freezing here, and we encountered some incredible rime icing, as displayed in the next few photographs.

It was very much the tops of the trees subject to the heaviest rime.

A closer view reveals almost snow-like accumulations. But this was not snow -
it was rime ice accumulating out of the freezing fog.

Roads were clear of ice, but the surrounding trees, hedges
and walls were heavy with rime.

Trees along-side the main Hog's Back road were heavy with over 2 inches of rime, accumulating along with the wind direction. Even fences did not escape.

The trees with Laura in for scale. The headlights of her car are almost faded out by the thick, freezing fog.

The wind had allowed rime to develop in all manner of strange formations. Here, the airflow around the horizontal fence bars created this horseshoe of rime!

The amount of rime on some thin twigs must have created considerable strain.

Another example of the rime collecting on thin twigs, sometimes over 2-3 inches deep.

Any finally, a few photographs from Weybridge on the afternoon of the 22nd December.

Traffic was flowing ok, although the fog had yet to thicken.

And when the fog had thickened, visibility dropped to around 100 metres.

Fog provide a spooky foreground to the background sheet of grey.