Definitions - n

Nacelle

The part of a wind generator that houses the generator, gearbox etc at the top of the tower.

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Nacreous Clouds

Clouds of unknown composition that have a soft, pearly luster and that form at altitudes about 25 to 30 km above the earth's surface. They are also called mother-of-pearl clouds.

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Natural Products

Natural Products are products made using natural organic ingredients and none factory processes. Often made by small independent local businesses or individuals.

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Negative Feedback

A process that results in a reduction in the response of a system to an external influence. For example, increased plant productivity in response to global warming would be a negative feedback on warming, because the additional growth would act as a sink for CO2, reducing the atmospheric CO2 concentration.

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Nekton

Animals, such as fish and whales, that move independently of water currents between the bottom and surface of the ocean.

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Net Metering

Net Metering is a method of crediting customers for electricity that they generate on site in excess of their own electricity consumption. Customers with their own generation offset the electricity they would have purchased from their utility. If such customers generate more than they use in a billing period, their electric meter turns backwards to indicate their net excess generation.

Depending on individual state or utility rules, the net excess generation may be credited to their account (in many cases at the retail price), carried over to a future billing period, or ignored.

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Nimbostratus

A dark, gray cloud characterized by more or less continuously falling precipitation. It is not accompanied by lightning, thunder, or hail.

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Nitrate

A compound containing nitrogen that can exist in the atmosphere or as a dissolved gas in water and which can have harmful effects on humans and animals. Nitrates in water can cause severe illness in infants and domestic animals. A plant nutrient and inorganic fertilizer, nitrate is found in septic systems, animal feed lots, agricultural fertilizers, manure, industrial waste waters, sanitary landfills, and garbage dumps.

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Nitrilotriacetic Acid

(NTA) A compound now replacing phosphates in detergents.

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Nitrogen Cycle

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Nitrogen Fixation

Conversion of atmospheric nitrogen gas into forms useful to plants and other organisms by lightning, bacteria, and blue-green algae; it is part of the nitrogen cycle.

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Non-linearity

Process without a simple proportional relation between cause and effect. The climate system contains many non-linear processes, resulting in a system with very complex behavior.

Note: Complex systematic behavior does not imply dramatic chaotic behavior; multiple cause and effect processes 'overlap' in their effect - much like waves in a sea, often canceling each other out and creating relative 'calm'. Although every once in a while you will get effects that mutually enhance each other and cause dramatic short or long term lived events or features in the climate (i.e. tornadoes, gulf streams, etc).

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Non-potable

Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents.

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Nonpoint Sources

Sources of pollution that do not originate at the point where pollution is detected, e.g.: agricultural runoff: precipitation and irrigation-related runoff of animal wastes and pesticides from crop and pasture lands. feedlot runoff: primarily precipitation-related discharge of animal wastes from concentrated livestock feeding areas. individual wastewater treatment system runoff: discharge of partially treated sewage from malfunctioning on-site septic systems. urban runoff: precipitation-related discharge of septic leachate, animal wastes, etc. from impervious surfaces, lawns, and other urban land uses. wildlife runoff: precipitation-related runoff of animal wastes from areas with high concentrations of wildlife (e.g., waterfowl).

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Null Electricity

Null Electricity is electricity that is stripped of its attributes and undifferentiated. No specific rights to claim fuel source or environmental impacts are allowed for null electricity.  Also referred to as commodity or system electricity.

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Null Hypothesis

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Nutrient Pollution

Contamination of water resources by excessive inputs of nutrients. In surface waters, excess algal production is a major concern.

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