Glossary |
Select a letter from the index given below,
to be shown those glossary items which begin with the same letter.
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R |
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Rain |
Precipitation of liquid water drops greater than 0.5 mm in diameter. In contrast to
showers, it is steadier and normally falls from stratiform (layer) cloud. |
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Rain day |
A rain day occurs when a daily rainfall of at least 0.2 mm is recorded. |
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Rainfall |
The total liquid product of precipitation or condensation from the atmosphere,
as received and measured in a rain gauge. |
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Reference Climate Station (RCS) |
A climatological station, the data of which are intended for the purpose
of determining climatic trends. This requires long periods (not less than
thirty years) of homogeneous records, where human-influenced environmental
changes have been and/or are expected to remain at a minimum. Ideally
the records should be of sufficient length to enable the identification
of secular (lasting for ages) changes of climate. |
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Relative humidity |
Is a traditional indicator of the air's moisture content. It is the ratio
of the amount of moisture actually in the air to the maximum amount of
moisture which the air could hold at the same temperature. Relative humidity
is normally expressed as a percentage and at saturation the relative humidity
will be very close to 100%. The air can hold more moisture at higher temperatures,
hence the relative humidity alone does not give an absolute measure of
moisture content. |
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Ridge |
A ridge is an elongated area of high pressure. It is indicated by rounded isobars
extending outwards from an anticyclone and has associated with it a ridge line. The
pressure at a point on the ridge is higher than at an adjacent point on either side
of the line. |
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