Glossary
A-D | E-L | M-O | P-R | S-T | U-Z
Aerosols
Airborne suspension of small particles.
Block Time
The time elapsed from start of taxi out at origin to the end of taxi in at destination.
Bunker Fuels (International)
Fuels consumed for international marine and air transportation.
Climate Model
A numerical representation of the climate system. Climate models are of two basic types: (1) static, in which atmospheric motions are neglected or are represented with a simple parameterization scheme such as diffusion; and (2) dynamic, in which atmospheric motions are explicitly represented with equations. The latter category includes general circulation models (GCMs).
Combustion Efficiency
Ratio of the heat released in combustion to the heat available from the fuel.
Contrail
Condensation trail (i.e., white line-cloud often visible behind aircraft).
Dp/F00
The ICAO regulatory parameter for gaseous emissions, expressed as the mass of the pollutant emitted during the landing/take-off (LTO) cycle divided by the rated thrust (maximum take-off power) of the engine.
Emission Index
The mass of material or number of particles emitted per burnt mass of fuel (for NOx in g of equivalent NO2 per kg of fuel; for hydrocarbons in g of CH4 per kg of fuel)
Energy Efficiency
Ratio of energy output of a conversion process or of a system to its energy input; also know as first-law efficiency.
Engine Pressure Ratio
The ratio of the mean total pressure at the last compressor discharge plane of the compressor to the mean total pressure at the compressor entry plane, when the engine is developing its take-off thrust rating (in ISA sea-level static conditions).
Greenhouse Gas
A gas that absorbs radiation at specific wavelengths within the spectrum of radiation (infrared) emitted by the Earth’s surface and by clouds. The gas in turn emits infrared radiation from a level where the temperature is colder than the surface. The net effect is a local trapping of part of the absorbed energy and a tendency to warm the planetary surface. Water vapor (H20), carbon dioxide (CO2), nitrous oxide (N20), methane (CH4), and ozone (03) are the primary greenhouse gases in the Earth’s atmosphere.
Landing/Take-Off (LTO) Cycle
A reference cycle for the calculation and reporting of emissions, composed of four power settings and related operating times for subsonic aircraft engines [Take-Off – 100% power, 0.7 minutes; Climb – 85%, 2.2 minutes; Approach – 30%, 4.0 minutes; Taxi/Ground Idle – 7%, 26.0 minutes].
Life-Cycle Cost
The cost of a good or service over its entire lifetime.
Mach Number
Speed divided by the local speed of sound.
Mitigation
An anthropogenic intervention to reduce the effects of emissions or enhance the sinks of greenhouse gases.
NOx
Oxides of nitrogen, defined as the sum of the amounts of nitric oxide (NO) and nitrogen dioxide (NO2) with mass calculated as if the NO where in the form of NO2.
Overall Efficiency (?)
The ratio between mechanical work delivered by an engine relative to the chemical energy provided from burning a fuel [? = (thrust x speed) / (specific combustion heat x fuel consumption rate)].
Ozone
A gas that is formed naturally in the stratosphere by the action of ultraviolet radiation on oxygen molecules. A molecule of ozone is made up of three atoms of oxygen.
Ozone Hole
A substantial reduction below the naturally occurring concentrations of ozone, mainly over Antarctica.
Ozone Layer
A layer of ozone gas in the stratosphere that shields the Earth from most of the harmful ultraviolet radiation coming from the Sun.
Particulate Mass Emission Index
The number of grams of particulate matter generated in the exhaust per kg of fuel burned.
Plume
The region behind an aircraft containing the engine exhaust.
Polar Stratospheric Clouds
Large, diffuse, ice-particle clouds that form in the stratosphere usually over Polar Regions.
Pressure Ratio
The ratio of the mean total pressure exiting the compressor to the mean total pressure of the inlet when the engine is developing take-off thrust rating in ISA sea level static conditions.
Radiative Forcing
A change in average net radiation (in W m-2) at the top of the troposphere resulting from a change in either solar or infrared radiation due to a change in atmospheric greenhouse gases concentrations; perturbance in the balance between incoming solar radiation and outgoing infrared radiation.
Rated Output
The maximum thrust available for take-off under normal operating conditions, as approved by the certificating authority.
Soot
Carbon-containing particles produced as a result of incomplete combustion processes.
Specific Fuel Consumption
The fuel flow rate (mass per time) per thrust (force) developed by an engine.
Stakeholders
Person or entity holding grants, concessions, or any other type of value which would be affected by a particular action or policy.
Stoichiometric Ratio
The fuel-air ratio at which all oxygen is consumed (approximately 0.068).
Stratosphere
The stably stratified atmosphere above the troposphere and below the mesosphere, at about 10-to 50-km altitude, containing the main ozone layer.
Susceptibility
Probability for an individual or population of being affected by an external factor.
Sustainable
A term used to characterize human action that can be undertaken in such a manner as to not adversely affect environmental conditions (e.g., soil, water quality, climate) that are necessary to support those same activities in the future.
Tropopause
The boundary between the troposphere and the stratosphere, usually characterized by an abrupt change in lapse rate (vertical temperature gradient).
Troposphere
The layer of the atmosphere between the Earth’s surface and the tropopause below the stratosphere (i.e., the lowest 10 to 18 km of the atmosphere) where weather processes occur.
Volatiles
Particles that evaporate at temperatures less than about 1000C.
Vulnerability
The extent to which climate change may damage or harm a system; it depends not only on a system’s sensitivity, but also on its ability to adapt to new climatic conditions.
Wake
The turbulent region behind a body or aircraft.
