Wildfires Flashcards
What is a wildfire?
uncontrolled fire that is wiping out large fields and areas of land. It is typically fires that started out of a lightning strike, or people carelessly starting it, or accidentally, or even arson that went unnoticed and got out of hand. These fires sometimes burn for days and weeks. They can wipe out an entire forest and destroy almost every organic matter in it. These fires tend to thrive in very warm and dry climates, rather than thick, moist rainforest types.
What is a crown fire?
A crown fires spread across the canopies and affects forested areas.
What is a surface fire?
A surface fire burns across surface vegetation.
What is a ground fire?
A ground fire burns beneath the ground in layers of dry organic peat.
What is the ladder effect?
The ladder effect describes the process of fires from the forest floor spreading to the tree canopy.
How does wind affect the nature of wildfires?
Wind directs or changes the direction of fire to areas with new fuels
The stronger the longer and narrower the fire will be
Ladder effect
How does topography affect the nature of wildfires?
Generally wildfires travel:
Ambient wind goes uphill
Fresh supply of oxygen
Heat and smoke rise - so the vegetation had often been dried out adding to more combustion
How does the aspect of the land affect the nature of wildfires?
Sun facing side will be drier and more likely to burn
How does humidity affect the nature of wildfires?
Lower humidity of less than 7% has a greater chance for fire.
Percentage of maximum water vapour in the air
Percentage of maximum water vapour in the air.
Relative humidity varies during the day and is lowest in the early afternoon.
How do season affect the nature of wildfires?
Summer heat makes fuel drier and provides richer oxygen than the winter seasons.
How does the temperature affect the nature of wildfires?
Conditions with higher temperatures tend to absorb moisture from fuels and make them catch fire.
This is why areas with lots of sun and higher temperatures tend to be more dry and have more fire events.
How do fuels affect the nature of wildfires?
Trees and vegetation with lots of moisture tend to slow down fires rather than speed them up. Vegetation with high oils and resin aid combustion and fires burn with more ease.
How does the space between fuels affect the nature of wildfires?
Burn more and spread faster if there are more fuels in close proximity. If fuels are sparsely distributed or are patchy, the fires tend to slow down.
This is why a common method of ending a fire is to create a ring of fuel free space around it.
