<Dd> A tornado - like vortex that forms from the stretching of vorticity due to the interaction of air flowing towards and upwards in a fire . </Dd> <Dt> Fire - return interval </Dt> <Dd> A small red booklet carried by U.S. firefighters on the firelines, as a quick reference on various firefighting topics . </Dd> <Dd> The part of a control line that is scraped or dug to mineral soil . Also called fire trail . More generally, working a fire is called being on the fireline . May also refer to a wet line, where water has been used to create a burn boundary in light fuels such as grass . </Dd>

A suppression action taken by a firefighter around the perimeter of a wildland fire is called