EAS 21700 Lecture Notes - Lecture 2: Wildfire, Water Vapor, Wind Direction
19 Feb 2019
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Document Summary
One of nature"s oldest phenomena: first when trees evolved and spread across the land, behavior changed when grasses evolved, changed again with an increase in charcoal in the sediment. Before humans, fires would burn until they ran out of fuel naturally: allowed humans to harness fires for their uses, helped populations spread across continents. Behavior of forest fires can be explained by three environmental factors: Fuel: complex and different in type, size, quantity, arrangement, and moisture content, types include leaves, twigs, decaying material, grass, shrubs, etc, fuel size affects ignition and movement, organic materials can dry out during droughts to become fuel. Topography: fuel moisture content is affected by location, mountainous areas circulate winds up canyons during daytime, fires preheat fuels upslope making it easier to spread. Weather: dominant influence, especially temperature, precipitation, relative humidity, and wind, fires common following droughts, fires burn more when humidity is lowest, wind direction and strength help preheat unburned materials.
