Saturday, December 23, 2006

Can you see this post through the Fog ??

Fog is very much in the news at the moment as we approach the Christmas period

There are tens of thousands of passengers delayed at airports like Heathrow. Some have no luggage, and others are sleeping on the floor. The story has occupied many hours on News24, and there are several issues which are of interest to geographers as a result. The fog has finally cleared today in Norfolk, although there are still patches in other parts of the country.

Modern aircraft can take off and land in fog, but safety considerations mean that there are longer delays between take-offs, which at Heathrow leads to major cancellations very quickly. There have to be larger gaps left on the ground in particular, and visibility should generally be around 500m, but in some airports it has been only 100 metres. I went up to Hunstanton yesterday to get the main Christmas supermarket shop done, and stock up on logs for the fire, and the visibility was only around 50 metres.

What is Fog ?

Well, there are actually several types of FOG.

In the UK, we mainly experience advection fog or radiation fog.

Fog requires moist air which is cooled below the dew point. This more usually happens at altitude to produce cloud droplets. Fog droplets are formed around some sort of condensation nucleus, such as dust, or ash, or salt or pollution in the form of aerosols.

When we breathe out on a cold morning, we are producing our own mini fogs, which persist for just a few seconds. The HIGH pressure has allowed for the fog to persist as there are light winds and the sun is low in the sky (the shortest day was during this period of fog, so there is no time for the heat of the sun to evaporate the fog)

Earlier in the week, fog caused the cancellation of the Carling Cup Quarter Final match between Arsenal and Liverpool.

Games can’t be played if the goals can’t be seen from the centre circle, or the referee can’t communicate with linesmen – there are also issues with being able to distinguish colours of the player’s kits… - Wikipedia article - BBC Weather article on Fog

Of course it’s not all bad news. How about this posting from the BBC’s “Have your Say” on the Fog…

Oh well, at least a significant pollution saving is to be had. It's good for the environment. Less planes equals less pollution (and so on). Long may the fog continue.

Mel Cabbit, Petersfield, United Kingdom

A few questions for you to ponder:

a) What is the difference between mist and fog ?

b) Does fog count as a form of precipitation ?

c) Why are the fogs on the Pacific coast of S. America of particular use to the inhabitants. has some useful information to help with part c) of the above

Keep an eye out for fog as we go through winter. Some of the fogs will be advection fog, and some radiation fog.

There are also features called FOG HOLLOWS (also Frost hollow). These are areas where the topography increases the chance of fogs forming.

Banner fog is a feature of my journey to school through the winter. At various points, the road crosses streams and hollows and fog tends to accumulate there, and then evaporate as the road rises up the hill.

Fog has also been linked with a number of unfortunate events in history. Can you identify any ?

Also making a Foggy PhotoJam with some wonderful FLICKR images which have been posted in the last few days: the immediacy of the web once again in action!

Looking for some FOGGY music to go with it. There’s a track by Frank Sinatra called “A Foggy Day”. Anyone know of other foggy music… “Misty” perhaps ?

And finally, the answer to the picture clue of earlier in the month.

The picture was of Eric Morecambe: someone who is very much associated with this time of year due to the enduring popularity of the Morecambe and Wise Christmas Shows, and the second picture is of cockles.

King’s Lynn has a large number of Chinese immigrants, many of whom work in the food processing industry locally. In February 2004, a number of Cocklers died in Morecambe Bay. This put the issue of migration and the use of migrant labour into the headlines.

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