 The fact of Australia's topography is that there's not much of it that's actually very flat. The speed of a fire on a slope can be very, very quick and can catch people unaware. So this is what you'd find with a fire that's spreading underneath the forest canopy. The higher the wind, the faster the fire will spread. On a steep hill what you'd find is that the flames are actually not that far above the level of the fuel and quite often are embedded in the fuel. That means that the exchange of energy is really efficient and that's what makes the fire spread that fast. With this fire here it's starting from a spot fire as you can see. Any fire that's actually spreading across the landscape will encounter upslopes where its speed will increase. So on a 10 degree slope it will spread twice as fast as a fire on flat ground under the same conditions and on a 20 degree slope it will spread four times as fast. The combination of that very strong wind on that very steep slope results in a horrendous rate of spread as the fire reaches the top of the ridge. If you are far enough downwind of the fire that you're not even aware that the fire is there, the first thing you may be aware of is things that are landing around you and if they're starting fires then it's too late for you to leave. There's no questioning the facts. Learn more at emergency.vic.gov.au Authorised by the Victorian Government, Melbourne.