Drought, Heat Waves, and Wildfires Flashcards
Broad Ridge
Stationary anticyclone creates a broad ridge that pushes warmer air further north than usual; poleward extension of contour lines indicates warmer than normal
Omega Block
Formed by the broad ridge; prevents cooler air from entering the ridge and re-routes cooler air around the ridge
Heat waves
No consistent exact definition but one governing body proposes the following conditions: 1. at least 3 consecutive days of daily max temps above the 97.5th percentile; 2. the average daily maximum temp is above the 97.5th percentile; 3. daily max temp is above the 81st percentile for every day in the period
Heat index
Takes into account temp and RH to assess risk to human body
Wet bulb temp
The coolest you can make the air by evaporating water; greater than or equal to 35 degrees C is threshold of survivability
Drought
“a period of abnormally dry weather sufficiently prolonged for the lack of water to cause serious hydrologic imbalance in the affected area.” Know 5 kinds and main causes
Evaporative Demand Drought Index
the thirst of the atmosphere; atmospheric influence of landscapes drying; unusually high evaporation causes moisture stress and drought–even if precip is near normal; can provide warnings for flash droughts and sustained droughts
Fire triangle
the rapid combination of oxygen with carbon, hydrogen, and organic material to produce flame, heat, and light.
Ground fires
burns organic matter beneath the surface little and is sustained by glowing combustion
Surface fires
spread with a flaming front and burn leaf litter; fallen branches and other fuels located at ground level
Crown fires
Most intense and most difficult to contain; burns through the top layer of foliage on a tree (canopy); reguires strong winds, steep slopes, and a heavy fuel load
Ladder fuels
Enable fire to climb trees (grasses to shrubs to tree canopy)
Firebrands
the spread of burning embers to start new blazes
