Help Topics - G

Gas

Material that is in the gaseous phase under the surrounding conditions.

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Global warming

The term 'climate change' is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, 'climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate.

Globe temperature

The temperature reported by a thermometer mounted inside a small matt black globe that measures the radiant heat in an area.

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Gravimetric analysis

The determination of the mass concentration of particulates using pre and post weighed filters. The sample filter is weighed before the measurement and again after the dust sample has been collected in the cassette. The difference between the weights is the mass of dust/particulate collected during the sampling interval. The total volume containing the dust sample is obtained from the flow rate of the device (usually a personal sampling pump) by multiplying the flow rate in l/min by the time in minutes. This gives a volume in cubic meters. The concentration value is therefore the mass divided by the volume and is usually expressed in mg/m³.

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