Wisps of magic in rare fog - and where to find it
Who'd have thought cold, heavy air could produce such atmosphere? Brad Chilby discloses the best spots to see valley fog
The Illawarra is blessed with an extraordinary diversity of landscapes. From pristine beaches and a rainforest-clad escarpment to a picturesque lake and rolling green hills, the region offers an incredible variety of scenery. Some of these landscapes bear a striking resemblance to those found in many other parts of the world.
The Illawarra escarpment plays a major role in shaping the region's weather patterns and, in turn, its flora and fauna. For photographers and weather enthusiasts, it provides some of the most spectacular and atmospheric scenery in NSW.
The photographs accompanying this article captures a relatively uncommon phenomenon in the Illawarra: valley fog. This dense form of radiation fog develops in low-lying gullies, valleys, basins and creek beds when cold, heavy air sinks and settles on the valley floor. As temperatures fall overnight, moisture within the trapped air condenses into tiny floating water droplets, forming a blanket of fog. A layer of warmer air above acts like a lid, preventing the colder air from mixing and allowing the fog to remain close to the ground.
Valley fog typically forms on calm, clear nights and is most often observed around sunrise under the right conditions. It generally begins developing during the evening, as was the case in this image, which was captured at sunset at Maddens Plains near Bulli Tops. This location is frequently cloaked in fog, although it is more commonly affected by precipitation fog, orographic fog (upslope fog) and advection fog (sea fog).
While valley fog is widespread throughout many inland regions of Australia, it is relatively uncommon in the Wollongong area, particularly across the coastal lowlands. Nevertheless, it does occasionally develop in suitable locations on top of the escarpment, especially around Bulli Tops and Helensburgh, as well as within the valleys of Albion Park, Jamberoo and Gerringong.
When conditions align, valley fog can add a touch of atmospheric magic to a scene, offering photographers the opportunity to create stunning images. Predicting valley fog can be challenging for most parts of the Illawarra and often comes down to a combination of experience, persistence and being in the right place at the right time. One of the best opportunities to witness valley fog locally is to explore the Jamberoo area in the early morning following a clear, calm night. Autumn and winter generally provide the most favourable conditions.
Perhaps the most important piece of advice is simply to keep your camera close at hand. Some of the most rewarding encounters with valley fog occur unexpectedly while travelling. A tripod is particularly useful as these scenes often unfold in the low light of dawn or dusk.
When using a tripod, keep your ISO as low as possible – ISO 100 is ideal to minimise image noise. An aperture of f/8 or f/11 will provide excellent depth of field for landscape photography, while a graduated neutral density filter can help balance the exposure between a bright sky and a darker foreground.
In mountainous regions further inland, valley fog is far more common and, during prolonged periods of stable weather, can persist for several days. In the Illawarra, its rarity only adds to its appeal. For those fortunate enough to witness it, valley fog serves as a reminder of the remarkable interplay between landscape, weather and light that makes this region such a rewarding place to photograph.
