Sunday, September 23, 2007

Fog in the Bog

A foggy ride down the bike trail between the blueberry fields.

You are heading along a main road at the speed limit or perhaps a bit above, as the traffic here tends to flow, when suddenly, lurching into the slow lane, is a wall of fog. A 100-acre area of undeveloped bog is sending its dense, misty arms into your headlights. It might be a good idea to slow down, everyone.

The bog remnants within this deltaic island, which also contains a growing city on steroids, create a patchwork of fog/no fog as you drive from one end to the other on cold, clear fall and winter evenings, especially if there have been recent rains to soak the ground.

There are different types of fog, classified by how they are formed. The patchy, low, dense fog that forms above bogs and other wetlands has the grabby sci-fi name, radiation fog. Radiation fog appears under clear, calm skies when infrared radiation (heat) escapes to the upper atmosphere and the air is cooled to its dew point. It is also known as ground fog, and often lies in photogenic ribbons only a metre or so thick just above the ground, like vaporous saloon doors. You can walk through blueberry patches and have your head above the clouds. Here in the bog you can have your own personal fogbank.

A second type of fog has the dull, technical name, advection fog. It forms when warm, humid air is cooled by coming into contact with a cooler surface below. These are the widespread ocean fogs that can creep up the arms of the river, or engulf the entire city. In December 2002, much of the Lower Mainland of British Columbia was blanketed in this type of fog for more than a week. It made for interesting effects in combination with Christmas lights.

Bogs, with their cold, water-saturated soils, are nurturing grounds for both fog types, and this island, historically, is one of the boggiest places on earth. It was Burns Bog's twin across the Fraser for thousands of years, until most of the bog was transformed into peat farms, initially, and later into cranberry and blueberry farms, which remain fog-friendly -- and subdivisions and industrial areas, which do not.

The extent, duration and challenge of foggy influxes confronting us these days are minor compared to what the original colonists endured scant decades ago, when huge areas disappeared into the murk for days at a time, and car headlights and motor vehicle safety regulations weren't what they are now. You would drive with the passenger door open with one eye on the ditch to know where the road was, or perch your most vocal child on the hood and hope she or he could scream out timely directions.

Personally, I enjoy fog, the way it softens the world, makes familiar places mysterious. For me it evokes a feeling of coziness and is a welcome change from the persistent, weak rain that can beset us at this time of year. Also, there is no light like the glow of the low autumn sun trying to penetrate a ground fog. The colours of fall foliage are strangely intensified in the absence of sharp shadows. A forest, field or garden can turn into a Group of Seven canvas.

Who knows how long the last large remnants will remain undeveloped, open spaces, foggy places, a reminder of the old, wild island. On this island, fog is not just a different kind of weather. It falls into a new category: it is Heritage Weather.

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