Which condition is considered a red flag for mixing height?

Which condition is considered a red flag for mixing height?

• A. <1,650 ft or >3,500 ft
• B. <2,000 ft or >5,000 ft
• C. <1,650 ft or >6,500 ft
• D. <2,500 ft or >7,000 ft

Answer: (C)

Mixing height is the vertical extent in the atmosphere where air thoroughly mixes and smoke can disperse. A red flag shows up when mixing height is outside safe, predictable ranges because that signals potential problems with smoke dispersion or with how the plume and winds will behave. The red-flag condition is when mixing height is very low or very high: less than 1,650 feet means the atmosphere isn’t mixing well, so smoke can linger near the ground and degrade air quality and visibility at and near the burn. More than 6,500 feet means the plume can rise into a very mixed, upper-level air layer, where winds can loft the smoke unpredictably and drift it long distances, complicating safety and smoke management. So, mixing heights under 1,650 feet or over 6,500 feet are the red-flag conditions, reflecting extreme limits in dispersion and plume behavior.

Mixing height is the vertical extent in the atmosphere where air thoroughly mixes and smoke can disperse. A red flag shows up when mixing height is outside safe, predictable ranges because that signals potential problems with smoke dispersion or with how the plume and winds will behave.

The red-flag condition is when mixing height is very low or very high: less than 1,650 feet means the atmosphere isn’t mixing well, so smoke can linger near the ground and degrade air quality and visibility at and near the burn. More than 6,500 feet means the plume can rise into a very mixed, upper-level air layer, where winds can loft the smoke unpredictably and drift it long distances, complicating safety and smoke management.

So, mixing heights under 1,650 feet or over 6,500 feet are the red-flag conditions, reflecting extreme limits in dispersion and plume behavior.