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The Todd Weather Folios are a collection of continental Australian synoptic charts that were published from 1879 to 1909. The charts were created by Sir Charles Todd's office at the Adelaide Observatory. In addition to the charts, the folios include clippings of newspaper articles and telegraphic and handwritten information about the weather.
Weather maps are created by plotting or tracing the values of relevant quantities such as sea level pressure, temperature, and cloud cover onto a geographical map to help find synoptic scale features such as weather fronts. The first weather maps in the 19th century were drawn well after the fact to help devise a theory on storm systems. [3]
A surface weather analysis is a type of weather map that depicts positions for high and low-pressure areas, as well as various types of synoptic scale systems such as frontal zones. Isotherms can be drawn on these maps, which are lines of equal temperature. Isotherms are drawn normally as solid lines at a preferred temperature interval. [2]
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] it is a
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]
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).
Autumn lasts between March and May and experiences changeable weather, where summer weather patterns gradually take on the shape of winter patterns. [ 48 ] The highest recorded maximum temperature in Tasmania was 42.2 °C (108.0 °F) at Scamander on 30 January 2009, during the 2009 south-eastern Australia heat wave .
Cloud-cover symbols used on weather teleprinters and aviation reports in the US [6] In the early 20th century, it was common for weather maps to be hand drawn. The symbols for cloud cover on these maps, like the modern symbols, were drawn inside the circle marking the position of the weather station making the measurements.