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A weather map, also known as synoptic weather chart, displays various meteorological features across a particular area at a particular point in time and has various symbols which all have specific meanings. [1] Such maps have been in use since the mid-19th century and are used for research and weather forecasting purposes.
In meteorology, the synoptic scale (also called the large scale or cyclonic scale) is a horizontal length scale of the order of 1,000 km (620 mi) or more. [1] This corresponds to a horizontal scale typical of mid-latitude depressions (e.g. extratropical cyclones ).
Scale of cloud cover measured in oktas (eighths) with the meteorological symbol for each okta. In meteorology, an okta is a scale of measurement used to describe the amount of cloud cover at any given location such as a weather station.
At the synoptic scale, the Coriolis acceleration acting on moving air masses (outside of the tropics) plays a dominant role in predictions. The phenomena typically described by synoptic meteorology include events such as extratropical cyclones, baroclinic troughs and ridges, frontal zones , and to some extent jet streams .
The definition of sustained winds recommended by the World Meteorological Organization (WMO) and used by most weather agencies is that of a 10-minute average at a height of 10 m (33 ft) above the sea surface. However, the Saffir–Simpson hurricane scale is based on wind speed measurements averaged over a 1-minute period, at 10 m (33 ft).
The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked as a dashed line or bold line. In the UK, Hong Kong [ 1 ] and Fiji, [ 2 ] it is represented by a bold line extended from a low pressure center [ 3 ] or between two low pressure centers; [ 4 ] in Macau [ 5 ] and Australia, [ 6 ...
Surface weather prognostic charts for mariners indicate the positions of high and low pressure areas, as well as frontal zones, up to five days into the future. Surface wind direction and speed is also forecast on this type of chart. Wave prognostic charts show the expected sea state at some future time. [2]
A surface weather analysis for the United States on October 21, 2006. By that time, Tropical Storm Paul was active (Paul later became a hurricane). Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations.