Editing Rain gauge (section)

===National coverage and modern gauges===
[[File:GeorgeJamesSymons(1838-1900).JPG|thumb|Symons in 1900]]

The meteorologist [[George James Symons]] published the first annual volume of ''British Rainfall'' in 1860. This pioneering work contained rainfall records from 168 land stations in England and Wales. He was elected to the council of the [[Royal Meteorological Society|British Meteorological Society]] in 1863 and made it his life's work to investigate rainfall within the British Isles. He set up a voluntary network of observers, who collected data which were returned to him for analysis. So successful was he in this endeavour that by 1866 he was able to show results that gave a fair representation of the distribution of rainfall and the number of recorders gradually increased until the last volume of British Rainfall which he lived to edit, for 1899, contained figures from 3,528 stations&nbsp;— 2,894 in [[England]] and [[Wales]], 446 in [[Scotland]], and 188 in [[Ireland]]. He also collected old rainfall records going back over a hundred years. In 1870 he produced an account of rainfall in the British Isles starting in 1725.

Due to the ever-increasing numbers of observers, standardisation of the gauges became necessary. Symons began experimenting with new gauges in his own garden. He tried different models with variations in size, shape, and height. In 1863 he began a collaboration with [[Michael Foster Ward]]<ref>[https://www.pelteret.co.za/content/000228/Col-Michael-Foster-Ward.pdf Colonel Michael Foster Ward]</ref> from [[Calne]], [[Wiltshire]], who undertook more extensive investigations. By including Ward and various others around Britain, the investigations continued until 1890. The experiments were remarkable for their planning, execution, and drawing of conclusions. The results of these experiments led to the progressive adoption of the well-known standard gauge, still used by the UK [[Met Office|Meteorological Office]] today, namely, one made of "...&nbsp;copper, with a five-inch funnel having its brass rim one foot above the ground&nbsp;..."<ref>:A short history of the British Rainfall Organisation by DE Pedgley, Sept 2002, published by The Royal Meteorological Society {{ISBN|0-948090-21-9}}</ref>

Most modern rain gauges generally measure the precipitation in [[millimetre]]s in height collected during a certain period, equivalent to [[litre]]s per square metre. Previously rain was recorded as inches or points, where one point is equal to 0.254&nbsp;mm or 0.01 of an inch.<ref>{{cite web |url=http://www.bom.gov.au/climate/data-services/content/faqs-elements.html |title=Observations |access-date=2024-01-22 |url-status=live |archive-url=https://web.archive.org/web/20171019062834/http://www.bom.gov.au/climate/data-services/content/faqs-elements.html |archive-date=2017-10-19 }}</ref>

Rain gauge amounts are read either manually or by [[automatic weather station]] (AWS). The frequency of readings will depend on the requirements of the collection agency. Some countries will supplement the paid weather observer with a network of volunteers to obtain precipitation data (and other types of weather) for sparsely populated areas.

In most cases the precipitation is not retained, but some stations do submit rainfall and snowfall for testing, which is done to obtain levels of pollutants.

Rain gauges have their limitations. Attempting to collect rain data in a [[tropical cyclone]] can be nearly impossible and unreliable (even if the equipment survives) due to wind extremes. Also, rain gauges only indicate rainfall in a localized area. For virtually any gauge, drops will stick to the sides or funnel of the collecting device, such that amounts are very slightly underestimated, and those of .01&nbsp;inches or .25&nbsp;mm may be recorded as a "[[trace (precipitation)|trace]]".

Another problem encountered is when the temperature is close to or below freezing. Rain may fall on the funnel and ice or snow may collect in the gauge, blocking subsequent rain. To alleviate this, a gauge may be equipped with an automatic electric heater to keep its moisture-collecting surfaces and sensor slightly above freezing.

Rain gauges should be placed in an open area where there are no buildings, trees, or other obstacles to block the rain. This is also to prevent the water collected on the roofs of buildings or the leaves of trees from dripping into the rain gauge after a rain, resulting in inaccurate readings. Rain gauges can help people comprehend the amount of precipitation fallen down in a certain period of time.