Our valley is one of Australia’s unofficial fog capitals, but why is that the case?
It starts with the landscape.
On still winter nights, cold air slides off the surrounding high ground and pools across the flat valley floor, causing temperatures to quickly drop.
The Bureau of Meteorology describes this as “radiation fog”, cold air sinking into valleys, especially where a stream or river adds moisture to the air, making them likely areas for fog formation.
Temperature only tells half the story.
Fog forms when the gap between air temperature and dew point closes entirely.
Too much wind, and you get low cloud instead, too little wind and dew sits on the grass but never lifts.
The Goulburn Valley’s vast network of irrigation channels, pastures, and crops keeps local humidity running high year-round, narrowing that temperature-dew point gap before the night has even cooled.
The valley creates its own fog conditions before the atmosphere has to do much work.
Once the fog settles in, winter’s weak sun rarely wins.
Fog can persist well beyond sunrise when it’s thick or when mid-level cloud has moved overhead, cutting off the solar warmth needed to burn it away.
Tuesday was a textbook example, with patches clinging on through the morning and into the early afternoon.
13°C