Minor Snow: Winter takes hold

June 5th, 2012
by Jo Law

This last pentad of Minor Snow coincides with the beginning of winter as reckoned by the meteorological model used in Australia. In the first 5 days of June, the lowest minimum temperature recorded at Bellambi (AWS) is 10.2ºC at 3.53am on the morning of June 5th and lowest maximum is 15.3ºC on June 3rd. The weather in the Illawarra has been affected by the ‘East Coast Lows’, that become prominent in winter. Low pressure systems formed on the Tasman Sea moving eastwards and northwards bringing precipitation to the coast. There is no time like a cold wet day to light up the hearth.

With the abundance of dried sticks stock-piled from last summer’s pruning and the win fall of the fell rotten ironbark from across the road last year, heating our house using the built-in slow combustion wood heater becomes an viable heating option. When the last rays of the sun start to disappear behind the escarpment around 3 in the afternoon, we gather newspaper, twigs, sticks and logs to build the fire. As the fire grows, bigger pieces are fed to the vigorous flames. When a sizable ironbark log has caught and is burning hot, the air vent is partially closed to slow down the combustion and the hot air is pushed through the vent into the room.

Fire occurs as a chemical process when oxygen (or an oxidizer) and fuel are raised to the ignition temperature (or flash point) of the material and rapid combustion begins. Combustion is an oxidization process when principally oxygen is combined with hydrogen and carbon forming water and carbon dioxide. In a wood fire, celluose begins to decompose when the material is raised to a temperature of around 260ºC. Water and volitate gasses are released (sometimes in combination with unburned particles as smoke). This oxidization leaves behind char (pure carbon) and ash (incombustible potassium, calcium and other materials). Energy is released as light and heat.

The oldest fossil records of wildfire dates back to 420 million years ago and is directly related to the availability of abundant oxygen in the atmosphere and the expansion of the earth’s then biomass. Strong evidence suggests that Homo Erectus were the first hominids to use fire in a controlled way some 400 thousand years ago. Today debates rage on about the energy efficiency and greenhouse emission of wood heaters . Most states have environment protection act that restricts households from generating excessive smoke. Wollongong Council defines excessive smoke as ’emission of a visible plume of smoke from a chimney for a continuous period of not less than 10 minutes, including a period of not less than 30 seconds when the plume extends at least 10 metres from the point at which the smoke is emitted from the chimney.’

A poorly lit fire emits toxic compounds such as carbon monoxide and particulates that are harmful to human health (more so than cigarette smoke) and pollutes the air (worse than car pollution). A clean and efficient fire has no smoke. Here are some tips to build a clean fire:

  • always burn dry or seasoned wood
  • fire should be burning fiercely before more fuel is added
  • open vents for 20 minutes when starting and refueling stove
  • fire should burn brightly and not allowed to burn (smolder) overnight
  • clean chimneys

On the last night of this pentad, our wood fire proved useful as friends joined us to spend an evening in our candle-lit living room during the power black out.

One Response to “Minor Snow: Winter takes hold”

  1. 1 Lucas
    June 10th, 2012 at 17:46

    yes, and beyond the technical side of fire – as Red says, it’s probably the reason why humans are social beings.

    We have to share a fire, and that means making up tall tales to tell each other long into the night!