Skip to main content

NWCG Glossary of Wildland Fire (PMS 205)

Term Steward Status Definition
heat low IWSC Incident Weather Subcommittee Approved An area of low pressure caused by intense heating of the earth's surface. High surface temperature causes air to expand and rise, resulting in low atmospheric pressure and induces a weak inflow of air at the surface. Air which rises in a heat low is very dry so clouds seldom form. Rising air above a heat low produces a warm upper level high and results in a net outflow of air aloft. Heat lows remain practically stationary over areas which produce them. 
heat of combustion FASC Fire Analysis Subcommittee Approved The heat energy resulting from the complete combustion of a fuel, expressed as the quantity of heat per unit weight of fuel. The high heat of combustion is the potential available, and the low heat of combustion is the high heat of combustion minus several losses that occur in an open system (primarily heat of vaporization of moisture in the fuel).
heat per unit area FASC Fire Analysis Subcommittee Approved Total amount of heat released per unit area as the flaming front of the fire passes, expressed as Btu/square foot; a measure of the total amount of heat released in flames.
heat probe ETSC Equipment/Technology Subcommittee Approved Apparatus used to detect heat.
heat release rate (consumed) IWSC Incident Weather Subcommittee Approved Total amount of heat produced per unit mass of fuel consumed per unit time.
heat release rate (released) IWSC Incident Weather Subcommittee Approved Amount of heat released to the atmosphere from the convective-lift fire phase of a fire per unit time.
heat transfer IWSC Incident Weather Subcommittee Approved Process by which heat is imparted from one body to another, through conduction, convection, and radiation.
Heat Trough IWSC Incident Weather Subcommittee Approved A Heat Low which is elongated in shape.
heat value IWSC Incident Weather Subcommittee Approved The total heat energy released during combustion, usually published as units of heat energy produced per unit mass of ovendry fuel consumed.
heat yield IWSC Incident Weather Subcommittee Approved The heat of combustion corrected for various heat losses, mainly the presence of moisture in the fuel. To a very close approximation, the quantity of heat per pound of fuel burned that passes through a cross section of the convection column above a fire that is burning in a neutrally stable atmosphere.
heavy equipment transport ETSC Equipment/Technology Subcommittee Approved Any ground vehicle capable of transporting a dozer, tractor, or other heavy piece of equipment.
heavy fuels FMSC Fuels Management Subcommittee Approved Fuels of large diameter such as snags, logs, large limbwood, which ignite and are consumed more slowly than flash fuels.
heel of the fire FISC Fire Investigation Subcommittee Approved That portion of a fire backing directly away from and in relatively close proximity to the ignition area. The slowest spreading portion of a fire edge and generally opposite the head.
height FMSC Fuels Management Subcommittee Approved The vertical measurement of vegetation from the top of the crown to ground level.
Height Above Ground Level (HAGL) GISC Geospatial Information Subcommittee Approved A height measured with respect to the underlying ground surface.
Height Above Sea Level (HASL) GISC Geospatial Information Subcommittee Approved Height above mean sea level in feet.
held line IOSC Incident Operations Subcommittee Approved All control line that still contains the fire when mopup is completed. Excludes lost line, natural barriers not backfired, and unused secondary lines.
helibase RWSC Rotor Wing Subcommittee Approved The main location within the general incident area for parking, fueling, maintenance, and loading of helicopters. It is usually located at or near the incident base.
helibase crew RWSC Rotor Wing Subcommittee Approved A crew of individuals who may be assigned to support helicopter operations.
helibucket AMC Aviation Management Committee Approved Specially designed bucket carried by a helicopter like a sling load and used for aerial delivery of water or fire retardants.
helicopter tender AMC Aviation Management Committee, ETSC Equipment/Technology Subcommittee Approved A ground service vehicle capable of supplying fuel and support equipment to helicopters.
helicopter type (water source) RWSC Rotor Wing Subcommittee Approved Largest helicopter type that can use the water source.
heliport AMC Aviation Management Committee Approved A permanent facility for the operation of helicopters which has been built to FAA standards and which is marked on aeronautical charts. Natural resource agencies refer to agency heliports as permanent helibases.
helipumper AMC Aviation Management Committee Approved Lightweight portable pump developed for transport by helicopter.
helispot AMC Aviation Management Committee Approved A natural or improved takeoff and landing area intended for temporary or occasional helicopter use.
Displaying 1201 - 1225 of 2700

NWCG Latest Announcements