The Following section is focused on the general properties that will influence fire ignition and behavior. If your background is not in fire science, this section will help to bring you up to speed on the three main factors that drive and control wildland fires. These three factors are fuels, weather and topography.

For our purposes, we will break these three facor into two groups. Weather and topography, and fuels.

The brief description (sweeping generalizations)

Weather - Dry conditions will produce more intense fire behavior than wet or humid conditions. Transient. Weather can describe patterns that change over months, or years, or it can be used to describe conditions that change over days, hours or even minutes. A large component of weather is wind, which can bring more oxygen to fuels, and can pre-heat fuels at the flaming front of a fire to drive out moisture.

Topography - Topography describes the lay of the land. Fires will progress more rapidly up steep slopes thadue to pre-heating of fuels ahead of the flaming front. An additional component of topography is aspect. Aspect is the compass direction in which a slope faces. South and west facing aspects receive more radiant heat from the sun, making them dryer than east or north aspects.

Fuels - are a critical component of fire. The size, arrangement, and moisture content of fuels are just a few of the factors that can influence how those fuels will behave when ignited, and if they will, if fact, ignite.

Most of the information contained in this section will focus on the "fuels" subsection mentioned above.

The importance of 1-hour Fuel moisture.

The diagrams depict a plan view of how an ignition source passes it heat energy to adjacent fuel cells.

High 1-hour fuel moisture (wet) click to enlarge

Low 1-hour fuel moisture (dry) click to enlarge

Moisture must be removed from fuels before they can combust. The amount of fuel moisture can greatly influence fire behavior. As a result, the fuel moisture of 1-hour time lag fuels has a large influence on fire behavior.

Video of ambient fuel moisture fuels (40%) (on left) vs oven dried fuels (on right). Time lapse video shows how high fuel moisture can impede fire spread and heat transfer. Click to download (12 Mb)