Weather Symbols

WMO STYLES & SYMBOLS

Professional meteorologists have traditionally plotted observations and produced forecast charts using a wide range of symbols, line styles and coloured areas, These have been internationally standardised for many years, and give true global interoperability, allowing the charts to be used irrespective of the user's language. The styles are defined in the publication: WMO No. 485: Manual on the Global Data Processing System, Part II, Appendix II.4, Graphical Representation of Data, Analyses and Forecasts. As well as English, it is available in French, Spanish and Russian.

Here are some sample WmoWeatherMaps and the corresponding data.

SURFACE PLOTTING MODEL

A 'plotting model' describes the layout on a map of a collection of individual measurements associated with one location and one time. Many dozens of locations are plotted on a single map or map layer. The model is defined in the above Manual. See NOAA NWS AMS for some examples. There are over 400 symbols used. Google "Weather symbol images". The most common are here GIF 3259x2055 or PDF pages 18-20.

There is a similar, simpler model for upper air plotting defined in the same Manual.

GRAPHIC REPRESENTATION OF DATA ON WEATHER CHARTS

There are several groups of styles, and several examples of each have been collected:

Vector symbols:

• Wind speed and direction:
  • NOAA GIFs 50x50
• Directions of movement of Ship or Swell:
  • UK low res vector symbols first 5 of PNG 849x257

Marker symbols, with a well-defined central location reference point:

• Total cloud cover:
  
  • Wikipedia search for "SVG symbol code" SVG 64x64, 200px, 500px, 1000px, 2000px PNGs Filenames are Cloud_cover_N.svg‎ 0=<N=<9
  • NOAA GIFs 31x31
  • Row 9 of UK low res vector symbols (WW W1/W2 N Sfloc) PNG 837x829
• Tropical Cyclones:
  • GIF 200px, slightly non-standard

Feature symbols, where the precise location reference point is not well defined:

• Present Weather from manual observations:
  • NOAA GIF and individual GIFs 55x55
  • UK page and individual GIFs 50x40 Filenames are NN.gif 00=<NN=<99
  • UK low res vector symbols (C Ch Cm Cl a WW)PNG 848x817 (WW W1/W2 N Sfloc)PNG 837x829
  • Wikipedia search for SVG symbol code SVG 55x55, 200px, 500px, 1000px, 2000px PNGsFilenames are:
    • Symbol_code_ww_NN.svg 00=<NN=<99 linked in decades, but
    • Symbol_drizzle_NN.svg‎ 50=<NN=<59,
    • Symbol_rain_NN.svg‎ 60=<NN=<69 and
    • Symbol_solid_precipitation_NN.svg‎ 70=<NN=<79 .
• Present Weather from automated observations:
  • GIF 877×544
  • UK low res vector symbols (WaWa) PNG 828x823
• Additional Present Weather from manual or automated observations:
  • UK low res vector symbols (W1W1) PNG 824x819
• Past Weather from manual observations:
  • NOAA GIFs 55x55
  • Row 7 of UK low res vector symbols (WW W1/W2 N Sfloc) PNG 837x829
• Past Weather from automated observations:
  • UK low res vector symbols PNG
• Cloud types (low, medium and high):
  • NOAA GIFs 40x40
  • Wikipedia search for SVG symbol code SVG 55x55, 200px, 500px, 1000px, 2000px PNGs Filenames are Clouds_HN.svg, 0=<N=<9
• Cloud Genus:
  • 4th row of UK low res vector symbols PNG 848x817
• Characteristic of Pressure tendency:
  • NOAA GIFs 30x30
• State of the Ground:
  • UK low res vector symbols (E E') PNG 786x760
• Others and individual GIFs 36x36, including current and obsolete ( PDF or MSWord format) or not WMO standard but historical or interesting such as photometeors

Line styles

• Fronts
• Other lines: WMO
  
• Jet Streams to be done

Regions

• Inter-Tropical Convergence Zone
• Areas of weather to be done
• Areas of weather (annotated with symbol) to be done

AVIATION STYLES & SYMBOLS

Aeroplane pilots have used Significant Weather Charts using a wide range of symbols, line styles and areas, designed to be viewed in low-light environments, and robust to repeated imperfect copying. These have been internationally standardised for many years, and give true global interoperability, allowing the charts to be used irrespective of the user's language. The styles are defined in the publication ICAO Annex 3 Met Services for International Air Navigation, which is also available as: WMO No 49: Met Services for International Air Navigation, Appendix 1, APP1-16, Paras 1-4. As well as English, it is available in French, Spanish, Russian, Arabic and Chinese.

Some sample SIgnificant Weather (SigWx) charts and the corresponding data are here.

Feature symbols:

• UK low res vector symbols PNG 779x361 Rows 3 - 10 PNG 786x760

Line styles

• Fronts
• Other lines
  
• Jet Streams

Regions

• Inter-Tropical Convergence Zone
• Areas of weather
• Areas of weather (annotated with symbol) to be done
• NOAA Aviation
• NOAA Aviation cloud cover

See ICAO symbols and line styles

Further Actions

At the Third Workshop on GIS/OGC Standards in Meteorology, Exeter, November 2010, we agreed to work towards publishing a definitive set of WMO symbols, probably on WikiMedia. IBL will make their symbol set available too.

When we have a reasonably good set, Envitia will try to put these in a portrayal registry, and then consider how to offer 'authoritative' references to well defined styles in SLDs, so that SLD rules can be provided, but alongside this have a 'But if you are a client good at drawing this then go ahead'.

Activity was kicked back into life by the first NASA Space Apps Challenge, May 2012, and by the Fourth Workshop on GIS/OGC Standards in Meteorology, Reading, March 2013, a complete set of both WMO and ICAO symbols and most line styles were made available in a public GitHub repository.

-- ChrisLittle - 08 May 2013