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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S |
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SALR |
The Saturated Adiabatic Lapse Rate (SALR) is the rate at which the temperature of a
parcel of air saturated with water vapour changes as the parcel ascends or descends.
The SALR is often taken as 1.5 degree Celsius per 1000ft, although the actual figure varies
according to the amount of water vapour present. |
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SCO |
Stands for Seasonal Climate Outlook.
These are outlooks of rainfall and temperature for three months ahead
and are updated every month. See
http://www.bom.gov.au/climate/ahead/ |
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Sea and Swell |
- Sea waves: waves generated by the wind blowing at the time,
and in the recent past, in the area of observation.
- Swell waves: waves which have travelled into the area of
observation after having been generated by previous winds in other
areas. These waves may travel thousands of kilometres from their origin
before dying away. There may be swell present even if the wind is
calm and there are no 'sea' waves.
- Wave period: the average time interval between passages of
successive crests (or troughs) of waves.
- Wave Height: Generally taken as the height difference between
the wave crest and the preceding trough.
- Wave Length: The mean horizontal distance between successive
crests (or troughs) of a wave pattern.
See the Sea and Swell tables for detailed
of sea and swell scales. |
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Sea breeze |
A local onshore wind. Cooler air from over the sea flows onto the shore to
replace the warm air rising over the land. On sunny days the land heats up
more quickly, and to a greater extent, than the sea. The air in contact with
the land warms and expands and the resulting changes in the pressure and
temperature differences and distributions cause the sea breeze circulation.
At night, when the land cools more quickly, and to a greater extent, than the
sea, the reverse land breeze circulation is set up. |
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Seasons |
In Australia, the seasons are defined by grouping the calendar months
in the following way:
- Spring - the three transition months September, October and November.
- Summer - the three hottest months December, January and February.
- Autumn - the transition months March, April and May.
- Winter - the three coldest months June, July and August.
These definitions reflect the lag in heating and cooling as the sun
appears to move southward and northward across the equator. They are
also useful for compiling and presenting climate-based statistics
on time scales such as months and seasons. |
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Showers |
Precipitation, often short-lived (but may last half an hour) and heavy, falling
from convective clouds. Usually begin and end suddenly. |
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Sleet |
Generally refers to a mixture of
rain and snow or falling snow that is melting into rain. |
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Smog |
Smog (contraction for 'smoke fog') is a fog in which smoke or other forms
of atmospheric pollutant have an important part in causing the fog to thicken,
and have unpleasant and dangerous physiological effects. |
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Snow |
Precipitation of ice crystals, most of which
are branched (sometimes star shaped). |
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Southern Oscillation Index (SOI) |
The Southern Oscillation Index (SOI) is calculated from the monthly or
seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
Click here for more information |
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Spring |
The three transition months September, October and November
(for the southern hemisphere). |
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Squall |
A squall comprises a rather sudden
increase of the mean wind speed which lasts for several minutes at least
before the mean wind returns to near its previous value. A squall may
include many gusts. |
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SST(s) |
Stands for Sea Surface Temperature(s), also SSTA(s) - Sea Surface Temperature
Anomalies.
Anomalies
in the surface temperature are associated with
changes in the heat exchange between atmosphere and ocean, or changes
in ocean currents or upwelling, and these changes can drive large changes
in rainfall and atmospheric circulation patterns. SSTAs are therefore
often strongly related to the development and maintenance of unusual
climate patterns, such as ENSO. |
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Storm Force Wind Warning |
A Storm Force Wind Warning is a statement which warns of winds averaging from 48 knots and up to 63 knots in coastal waters and high seas areas. |
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Stratosphere |
Layer of the atmosphere between about 10 and 50 kilometres above the ground. |
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Stratus cloud |
Low cloud forming a uniform layer. |
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Strong Wind Warning |
A Strong Wind Warning is a statement which warns of winds averaging from 26 knots and up to 33 knots in coastal waters.
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Summer |
The three hottest months December,
January and February (for the southern hemisphere). |
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Sunshine |
Direct radiation from the sun,
as opposed to the shading of a location by clouds or by other obstructions. |
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Supercell |
A persistent, single, intense updraught
and downdraught coexisting in a thunderstorm. |
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