logging in or signing up unit 6 Paola Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 169 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: February 28, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript UNIT 6: UNIT 6 Topographic Influences on Fire BehaviorUNIT 6 Objectives: UNIT 6 Objectives 1. Describe how topography affects fuels and their availability for combustion. 2. Describe how topography can affect the direction and rate of spread of wildland fires. 3. Describe how changes in fuels and topography can provide full and partial barriers to the spread of wildland fires.UNIT 6 Objectives: UNIT 6 Objectives 4. Explain the chimney effect in canyon topography. 5. Describe how slope percent can be determined or estimated in the field.Topographic Features STWB Fig 1 (p. 149): Topographic Features STWB Fig 1 (p. 149) Elevation Ridge Canyon Slope Aspect Intersecting drainages Box canyon Barrier Shape of country (contours) Topographic Map: Topographic Map SADDLE INTERSECTING DRAINAGE BARRIER RIDGE Elevation Above Sea Level: Elevation Above Sea Level 10,000 FEET Snow Tundra Timber Shrub Grass Sea LevelFires on Slope Reaching 10 Acres +: Fires on Slope Reaching 10 Acres +Fires Starting at Base of Slope Become the Largest Fires: Fires Starting at Base of Slope Become the Largest Fires Statistically, fires that start low on a slope get big. Why? Availability of FuelEffect of Aspect on Fuel Temperature and Moisture: Effect of Aspect on Fuel Temperature and Moisture Definition of Aspect? STWB Fig 2 (p. 151) Direction a slope is facing In general, south & southwest aspects are most favorable for fire start and spread lightest fuels lowest fuel moisture highest average temperature earlier curing of fuels earlier snow meltFire Occurrence by Aspect: Fire Occurrence by AspectMicro-climate Conditions: Micro-climate Conditions Fire behavior can change due to site-specific conditions at all elevations Fuel type and availability can be affected by micro-climate conditions due to: localized weather patterns product of accumulative water local soil and terrain factorsSlope Affects Fire Behavior: Slope Affects Fire Behavior PREHEATING FRESH AIR FASTER IGNITION AND SPREAD DRAFT BURNING CHUNKS ROLLING DOWN SLOPEEffect of Slope on Flame Length and Rate of Spread: Effect of Slope on Flame Length and Rate of Spread If fuels and wind are constant, the flame length and rate of spread will increase as the slope becomes steeperWedge Shape Fire Pattern: Wedge Shape Fire PatternSlope Reversal: Slope ReversalSlope Reversal: Slope ReversalSlope Reversal: Slope ReversalFires in the Bottom of Narrow Canyons: Fires in the Bottom of Narrow Canyons Heat & mass transfer Stable air conditions Air flowIntersecting Drainages: Intersecting Drainages Which direction will the fire spread?Barriers to Fire Spread: Barriers to Fire Spread Definition of a Barrier: Areas that lack available fuels, because of higher fuel moistures or sparse fuels Types of Barriers Rocks or bare soil conditions Lakes, streams, and moist soil situations Roads, trails, and other improvements Change in fuel type and fuel moisture Previously burned areasBarriers to Fire Spread: Barriers to Fire Spread LAKE BURN FUEL TYPE ROCK ROADPartial Barriers: Partial Barriers change in fuel conditions that offers only a partial barrier by slowing the spread of fire Examples: early morning dew on fine fuels retards fire spread in a meadow until afternoon green grasses in the spring will be fire resistant until they dry out in the summer north-facing slopes early in the season Chimney Effect: Chimney Effect Chimney effect occurs under the following conditions: Unstable air conditions at the surface cause a convection current through the canyon Air is drawn in a the base of the canyon to support the convection currents Fuels are available to support a rapid burnout in the head of the canyonChimney Effect: Chimney Effect Estimating Slope: Estimating Slope Clinometer/Abney Measurement Slope Meter (STWB Fig. 3 p. 156) CalculationsUNIT 6 Objectives: UNIT 6 Objectives 1. Describe how topography affects fuels and their availability for combustion. 2. Describe how topography can affect the direction and rate of spread of wildland fires. 3. Describe how changes in fuels and topography can provide full and partial barriers to the spread of wildland fires.UNIT 6 Objectives: UNIT 6 Objectives 4. Explain the chimney effect in canyon topography. 5. Describe how slope percent can be determined or estimated in the field. You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
unit 6 Paola Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 169 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: February 28, 2008 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript UNIT 6: UNIT 6 Topographic Influences on Fire BehaviorUNIT 6 Objectives: UNIT 6 Objectives 1. Describe how topography affects fuels and their availability for combustion. 2. Describe how topography can affect the direction and rate of spread of wildland fires. 3. Describe how changes in fuels and topography can provide full and partial barriers to the spread of wildland fires.UNIT 6 Objectives: UNIT 6 Objectives 4. Explain the chimney effect in canyon topography. 5. Describe how slope percent can be determined or estimated in the field.Topographic Features STWB Fig 1 (p. 149): Topographic Features STWB Fig 1 (p. 149) Elevation Ridge Canyon Slope Aspect Intersecting drainages Box canyon Barrier Shape of country (contours) Topographic Map: Topographic Map SADDLE INTERSECTING DRAINAGE BARRIER RIDGE Elevation Above Sea Level: Elevation Above Sea Level 10,000 FEET Snow Tundra Timber Shrub Grass Sea LevelFires on Slope Reaching 10 Acres +: Fires on Slope Reaching 10 Acres +Fires Starting at Base of Slope Become the Largest Fires: Fires Starting at Base of Slope Become the Largest Fires Statistically, fires that start low on a slope get big. Why? Availability of FuelEffect of Aspect on Fuel Temperature and Moisture: Effect of Aspect on Fuel Temperature and Moisture Definition of Aspect? STWB Fig 2 (p. 151) Direction a slope is facing In general, south & southwest aspects are most favorable for fire start and spread lightest fuels lowest fuel moisture highest average temperature earlier curing of fuels earlier snow meltFire Occurrence by Aspect: Fire Occurrence by AspectMicro-climate Conditions: Micro-climate Conditions Fire behavior can change due to site-specific conditions at all elevations Fuel type and availability can be affected by micro-climate conditions due to: localized weather patterns product of accumulative water local soil and terrain factorsSlope Affects Fire Behavior: Slope Affects Fire Behavior PREHEATING FRESH AIR FASTER IGNITION AND SPREAD DRAFT BURNING CHUNKS ROLLING DOWN SLOPEEffect of Slope on Flame Length and Rate of Spread: Effect of Slope on Flame Length and Rate of Spread If fuels and wind are constant, the flame length and rate of spread will increase as the slope becomes steeperWedge Shape Fire Pattern: Wedge Shape Fire PatternSlope Reversal: Slope ReversalSlope Reversal: Slope ReversalSlope Reversal: Slope ReversalFires in the Bottom of Narrow Canyons: Fires in the Bottom of Narrow Canyons Heat & mass transfer Stable air conditions Air flowIntersecting Drainages: Intersecting Drainages Which direction will the fire spread?Barriers to Fire Spread: Barriers to Fire Spread Definition of a Barrier: Areas that lack available fuels, because of higher fuel moistures or sparse fuels Types of Barriers Rocks or bare soil conditions Lakes, streams, and moist soil situations Roads, trails, and other improvements Change in fuel type and fuel moisture Previously burned areasBarriers to Fire Spread: Barriers to Fire Spread LAKE BURN FUEL TYPE ROCK ROADPartial Barriers: Partial Barriers change in fuel conditions that offers only a partial barrier by slowing the spread of fire Examples: early morning dew on fine fuels retards fire spread in a meadow until afternoon green grasses in the spring will be fire resistant until they dry out in the summer north-facing slopes early in the season Chimney Effect: Chimney Effect Chimney effect occurs under the following conditions: Unstable air conditions at the surface cause a convection current through the canyon Air is drawn in a the base of the canyon to support the convection currents Fuels are available to support a rapid burnout in the head of the canyonChimney Effect: Chimney Effect Estimating Slope: Estimating Slope Clinometer/Abney Measurement Slope Meter (STWB Fig. 3 p. 156) CalculationsUNIT 6 Objectives: UNIT 6 Objectives 1. Describe how topography affects fuels and their availability for combustion. 2. Describe how topography can affect the direction and rate of spread of wildland fires. 3. Describe how changes in fuels and topography can provide full and partial barriers to the spread of wildland fires.UNIT 6 Objectives: UNIT 6 Objectives 4. Explain the chimney effect in canyon topography. 5. Describe how slope percent can be determined or estimated in the field.