Firefighters at a grass fire
Firefighters at a grass fire

Grass fire behaviour and flame

This ongoing study is focused on measurement of rate of spread, flame residence time and vertical flame temperature variation during grass fires. Flame temperature measurements and rate of spread observations have been made on prescribed burns for grassland restoration carried out by the Ontario Ministry of Natural Resources in cooperation with local community groups throughout southern and central Ontario. Measurements have also been carried out on large prescribed fires south of Sudbury at Burwash (where range is being burned to encourage the growth of browse for elk). In 1997 flame temperature and residence time observations were made on savanna fires in Kenya as part of the AFARI project.

This work has shown that flame residence times in grass fuels are on the order of about 15 seconds and maximum temperatures (observed at the base of the flame) are around 800 to 1000 °C.

Grass fire temperatures
Flame front after passing through a 3 m high
thermocouple tower at the Ojibway prairie grass burn
(Windsor) 2001.
Intermittent torching
Flame front after passing through a temperature
measurement array mounted on a triangular tower
during the Matchedash burn (2000)
Grass fire temperatures
A typical temperature trace of a flame front during a grass fire