CPFM CPFM Weather & Atmospheric Conditions

Question 1

What wind speed range is generally considered acceptable for conducting prescribed burns?

Accepted Answer

5–15 mph

Answer

Wind speeds of 5–15 mph are generally acceptable for prescribed burns as they provide adequate smoke dispersal without causing excessive spotting.

Question 2

What atmospheric condition traps smoke near the ground by placing warm air above cooler air?

Accepted Answer

Temperature inversion

Answer

A temperature inversion reverses the normal atmospheric temperature gradient, preventing vertical mixing and trapping smoke near the surface.

Question 3

What relative humidity level is typically considered the minimum threshold for safe prescribed burning?

Accepted Answer

25–30%

Answer

Relative humidity below 25–30% significantly increases fire behavior unpredictability and the risk of losing control of a prescribed burn.

Question 4

What does the Haines Index measure in relation to prescribed fire?

Accepted Answer

Potential for large fire growth

Answer

The Haines Index combines lower atmospheric stability and moisture levels to indicate the potential for large, erratic fire development.

Question 5

Which weather phenomenon poses the greatest risk of causing spotting (fires starting outside the burn unit) during a prescribed burn?

Accepted Answer

Gusty, erratic winds

Answer

Gusty, erratic winds can carry burning embers unpredictably far beyond control lines, igniting spot fires outside the intended burn area.

CPFM - Certified Prescribed Fire Manager Practice Test