GLOSSARY
( ABC | DEF | GHI | JKL | MNO | PQR | STU | VW | XYZ )
We hear wind and weather words daily. But a few words may escape memory, and some that we use frequently might remain unclear. Take the word “gale,” for example, which is used to describe a strong wind. Did you know that “gale” has a specific scientific definition? A moderate gale refers to wind that blows between 28 and 33 knots (about 32-38 mph), the kind of wind that shakes trees and pushes you when you walk against it. In a “fresh” gale, which is even stronger, twigs break off the trees. Branches fall off when “strong” gales blow through, and a “whole” gale can cause trees to be uprooted. So the next time you hear someone say, “It’s blowing a gale out there,” you can reply, “What kind of gale?”
Admiral Sir Francis Beaufort (1774-1857) of the British navy created the Beaufort Scale to describe different wind effects on a sailing vessel. You can imagine that a sailor would want to know what kinds of winds are blowing. Later, Beaufort’s scale was expanded to include descriptions of the wind’s effects on land as well.
Air Pollution - Air with contaminants in it that prevent the air from dispersing as it normally would, and interfere with biological processes.
Alternative Energy - A popular term for “non-conventional” energy like renewables.
Asynchronous Generator - A type of electric generator that produces alternating current (AC) electricity to match an existing power source.
Battery - An energy storage device made up of one or more electrolyte cells. An electrolyte is a non-metallic conductor that carries current.
Breeze - Wind classified as light, gentle, moderate, fresh, or strong. To see the corresponding wind speeds for each of these, look at the Beaufort Scale above.
Carbon Dioxide (CO2) - A colorless, odorless noncombustible gas present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass), by respiration, which is a slow combustion in animals and plants, and by the gradual oxidation of organic matter in the soil. It is a greenhouse gas that contributes to global climate change.
Carbon Monoxide (CO) - A colorless, odorless but poisonous combustible gas. Carbon monoxide is produced in the incomplete combustion of carbon and carbon compounds, for example, fossil fuels like coal and petroleum.
Central Power Plant - A large power plant that generates power for distribution to multiple customers.
Chemical Energy - The energy liberated in a chemical reaction, as in the combustion of fuels.
Circuit - A device, or system of devices, that allows electrical current to flow through and voltage to occur across positive and negative terminals.
Circuit Breaker - A device used to interrupt or break an electrical circuit when an overload condition exists. Circuit breakers are used to protect electrical equipment from potential damage.
Climate - The prevailing or average weather conditions of a geographic region.
Conductor - The material through which electricity is transmitted, such as an electrical wire.
Conduit - A tubular material used to encase and protect electrical conductors.
Constant-Speed Wind Turbines - Wind turbines that operate at a constant RPM (rotor revolutions per minute). They are designed for optimal energy capture at a specific rotor diameter and at a particular wind speed.
Conventional Fuel - The fossil fuels: coal, oil, and natural gas.
Converter - A device for transforming electricity to a desired quality and quantity.
Cycle - In alternating current electricity, the current flows in one direction from zero to a maximum voltage, then goes back down to zero, then to a maximum voltage in the opposite direction. This comprises one cycle. The number of complete cycles per second determines the current frequency. In the United States the standard for alternating current is 60 cycles.
Cyclone - Air spinning inward toward centers of low air pressure. Cyclones spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Deregulation - The process of changing policies and laws of regulation in order to increase competition among suppliers of commodities and services. The Energy Policy Act initiated deregulation of the electric power industry in 1992.
Direct Current - A type of electricity transmission and distribution by which electricity flows in one direction through the conductor. Usually the electricity is a relatively low voltage and high current. Direct current is abbreviated as DC.
Distribution - The process of distributing electricity. Distribution usually refers to the portion of power lines between a utility’s power pole and transformer and a customer’s point of connection.
Doldrums - A narrow, virtually windless zone near the Equator, created as heated air rises upward, leaving the ocean’s surface calm and glassy.
Downburst - A severe localized downdraft from a thunderstorm. Also called a microburst.
Downwind Wind Turbine - A horizontal axis wind turbine in which the rotor is downwind of the tower.
Electricity - The energy of moving electrons, the current of which is used as a source of power.
Electricity Generation - The process of producing electricity by transforming other forms or sources of energy into electrical energy. Electricity is measured in kilowatt hours (kWh).
Emission - A substance or pollutant emitted as a result of a process.
Energy - The capacity for work. Energy can be converted into different forms, but the total amount of energy remains the same.
Energy Storage - The process of storing or converting energy from one form to another for later use. An example of a storage device is a battery.
Environment - All the natural and living things around us. The earth, air, weather, plants, and animals all make up our environment.
Fossil Fuels - Fuels formed in the ground from the decayed remains of dead plants and animals. It takes millions of years to form fossil fuels. Oil, natural gas, and coal are fossil fuels.
Frequency - The number of cycles through which an alternating current passes per second, measured in hertz.
Fuel - Any material that can be consumed to make energy.
Gearbox - A protective casing for a system of gears.
Generator - A device for converting mechanical energy to electrical energy.
Gigawatt (GW) - A unit of power equal to 1 million kilowatts.
Global Warming - A term used to describe the increase in average global temperatures due to the greenhouse effect.
Green credit - Green credits are a new way to purchase renewable electric generation that divides the generation into two separate products: the commodity energy and the renewable attributes. The green credit represents the renewable attributes of a single megawatt of renewable energy. Also known as green tags, renewable energy credits, or renewable energy certificates.
Green Power - A popular term for energy produced from renewable energy resources.
Greenfield - A site on which a power plant has not previously existed.
Greenhouse Effect - The heating effect resulting from long wave radiation from the sun being trapped by greenhouse gases that have been produced from natural and human sources.
Greenhouse Gases - Gases such as water vapor, carbon dioxide, methane, and low-level ozone that are transparent to solar radiation, but opaque to long wave radiation. These gases contribute to the greenhouse effect.
Grid (also “Power Grid” and “Utility Grid”) - A common term referring to an electricity transmission and distribution system.
Gust - A sudden brief increase in the speed of the wind.
Hertz (Hz) - A measure of the number of cycles or wavelengths of electrical energy per second. The United States electricity supply has a standard frequency of 60 hertz.
Horizontal-Axis Wind Turbines - Turbines on which the axis of the rotor’s rotation is parallel to the wind stream and the ground.
Jet Stream - A meandering and relatively narrow belt of strong winds embedded in the normal wind flow, generally found at high altitudes.
Joule (J) - A metric unit of energy or work. One joule per second equals 1 watt.
Kilowatt (kW) - A standard unit of electrical power equal to 1,000 watts.
Kilowatt-Hour (kWh) - A unit or measure of electricity supply or consumption of 1,000 watts over the period of one hour.
Kinetic Energy - Energy available as a result of motion. (Kinetic energy is equal to one half the mass of the body in motion multiplied by the square of its speed.)
Knot - One nautical mile per hour (1.15 MPH).
Landman - An in-house or independent land management consultant who negotiates terms of land leases with land owners.
Leading Edge - The surface part of a wind turbine blade that first comes into contact with the wind.
Lift - The force that pulls a wind turbine blade.
Mean Power Output (of a Wind Turbine) - The average power output of a wind energy conversion system at any given mean wind speed.
Mean Wind Speed - The average wind speed over a specified time period and height above the ground.
Mechanical Energy - The energy possessed by an object due to its motion (kinetic energy) or its potential energy.
Median Wind Speed - The wind speed with 50% probability of occurring.
Megawatt (MW) - The standard measure of electric power plant generating capacity. One megawatt is equal to one thousand kilowatts or 1 million watts.
Megawatt-hour (MWh) - 1,000 kilowatt-hours or 1 million watt-hours.
Met Tower - Meteorological towers erected to verify the wind resource found within a certain area of land.
Nacelle - The cover for the gearbox, drive train, and generator of a wind turbine.
Natural Gas - A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits. It generally contains a high percentage of methane, varying amounts of ethane, and inert gases. Natural gas is used as a heating fuel and for electricity generation.
Nitrogen Oxides (NOx) - The products of all combustion processes formed by the combination of nitrogen and oxygen. Nitrogen oxides and sulfur dioxide are the two primary causes of acid rain.
Non-Renewable Fuels - Fuels that cannot be easily renewed or reproduced, such as oil, natural gas, and coal.
Oil (fuel) - A product of crude oil that is used for space heating, diesel engines, and electricity generation.
Peak Wind Speed - The maximum instantaneous wind speed that occurs within a specific period of time.
Power - Energy that is capable or available for doing work.
Power Grid (also “Utility Grid”) - A common term referring to an electricity transmission and distribution system.
Power Quality - Stability of frequency and voltage and lack of electrical noise on the power grid.
Prevailing Wind Direction - The direction from which the wind predominantly blows as a result of the seasons, high and low pressure zones, the tilt of the earth on its axis, and the rotation of the earth.
Radioactive Waste - Materials left over from making nuclear energy. Radioactive waste can damage or destroy living organisms if it is not stored safely.
Recycling - The process of converting into new products materials that are no longer useful as they were originally designed.
Renewable Energy - Energy derived from resources that are regenerative or that cannot be depleted. Types of renewable energy resources include wind, solar, biomass, geothermal, and moving water.
Restructuring - The process of changing the structure of the electric power industry from one of a guaranteed monopoly that is regulated to one of open competition between power suppliers.
Rotor - The blades and other rotating components of a wind energy conversion turbine.
Solar Energy - Electromagnetic energy transmitted from the sun (solar radiation).
Solid Fuels - Any fuel that is in solid form, such as wood, peat, lignite, coal, and manufactured fuels such as pulverized coal, coke, charcoal briquettes, and pellets.
Step-Up Gearbox - A step-up gearbox increases turbine electricity production in stages by increasing the number of generator revolutions produced by the rotor revolutions.
Sulfur Dioxide (SO2) - A colorless gas released as a by-product of combusted fossil fuels containing sulfur. The two primary sources of acid rain are sulfur dioxide and nitrogen oxides.
Sustainable Energy - Energy that takes into account present needs while not compromising the availability of energy or a healthy environment in the future.
Trade Wind - The consistent system of prevailing winds occupying most of the tropics. They constitute the major component of the general circulation of the atmosphere. Trade winds blow northeasterly in the Northern Hemisphere and southeasterly in the Southern Hemisphere. The trades, as they are sometimes called, are the most persistent wind system on earth.
Turbine - Also see "Wind Turbine." A term used for a wind energy conversion device that produces electricity.
Turbulence - A swirling motion of the atmosphere that interrupts the flow of wind.
Utility Grid - Also see "Power Grid." A common term referring to an electricity transmission and distribution system.
Variable-Speed Wind Turbines - Turbines in which the rotor speed increases and decreases with changing wind speeds. Sophisticated power control systems are required on variable speed tubines to insure that their power maintains a constant frequency compatible with the grid.
Volt - A unit of electrical force.
Voltage - The amount of electromotive force, measured in volts, that exists between two points.
Watt (W) - The rate of energy transfer (from an outlet to an appliance, for example). Wattage is calculated by multiplying voltage by current.
Watt-Hour (Wh) - A unit of electricity consumption of one watt over the period of one hour.
Wind - Moving air. The wind's movement is caused by the sun's heat, the earth, and the oceans, forcing air to rise and fall in cycles.
Wind Energy - (Also see "Wind Power") Power generated by converting the mechanical energy of the wind into electrical energy through the use of a wind generator.
Wind Energy Conversion System (WECS) - An apparatus for converting wind energy to mechanical energy, making it available for powering machinery and operating electrical generators.
Wind Farm - A piece of land on which wind turbines are sited for the purpose of electricity generation.
Wind Generator - A wind energy conversion system designed to produce electricity.
Wind Power -( Also see "Wind Energy") Power generated by converting the mechanical energy of the wind into electrical energy through the use of a wind generator.
Wind Power Plant - A group of wind turbines interconnected to a common utility system.
Wind Resource Assessment - The process of characterizing the wind resource and its energy potential for a specific site or geographical area.
Wind Rose - A diagram that indicates the average percentage of time that the wind blows from different directions, on a monthly or annual basis.
Wind Speed - The rate of flow of wind when it blows undisturbed by obstacles.
Wind Speed Frequency Curve - A curve that indicates the number of hours per year that specific wind speeds occur.
Wind Speed Profile - A profile of how the wind speed changes at different heights above the surface of the ground or water.
Wind Turbine - A term used for a wind energy conversion device that produces electricity.
Wind Turbine Rated Capacity - The amount of power a wind turbine can produce at its rated wind speed.
Wind Velocity - The wind speed and direction in an undisturbed flow.
Windmill - A wind energy conversion system that is used to grind grain. However, the word windmill is commonly used to refer to all types of wind energy conversion systems.
Windpower Profile - The change in the power available in the wind due to changes in the wind speed or velocity.
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