一些历史标准形成由于仪器。云量观测设置基于okta,第八分数的天空覆盖开销在过去小时(也许8观测都被早期的仪器/记录/观察者)。这导致美国国家气象局[使用][1]这个表报告和预测:[!(NWS)[2]]同样[2],[翻斗式雨量计]的[3]以0.01英寸(0.25毫米)的增量,这影响降水的类别是如何选择的。[杂志的这篇文章][4]指出:>天气观测,细雨是归类为(a)很轻,>组成的分散滴不完全湿>暴露面,不管时间;(b)“光”的速度>秋季从跟踪到每小时0.25毫米:(c) "温和" >下降的速度是每小时0.25 -0.50毫米:(d)“重”>下降的速度是每小时超过0.5毫米。当降水量>等于或超过每小时1毫米,全部或部分的降水是>通常下雨;然而,真正的细雨一样严重下降1.25 >毫米每小时已被观察到。按照惯例,细雨滴直径> 0.5毫米或更少”显示,有大量的连接在雨的定义/细雨强度0.25毫米基线。然而,尽管许多组织可能从这个框架,没有理由其他组织必须建立他们的措辞和图标这些历史标准。 They may wish to have more or fewer categories in their forecasts. For example, Wunderground's API table shows that [[current link][6] now access protected, original information [here][5]]: [![enter image description here][7]][7] They use just four cloud coverage icon categories, while their forecast wording options include clear, cloudy, mostly cloudy, mostly sunny, partly cloudy, partly sunny, and scattered clouds. So they don't appear to match the standard NWS table. So long story short: **There are some historical standards, but sites can take liberties in reporting it how they wish. Looking through some of the APIs, it would definitely be nice if they would better indicate the actual criteria they use!** [1]: http://www.weather.gov/bgm/forecast_terms [2]: https://i.stack.imgur.com/2DzqR.png [3]: https://en.wikipedia.org/wiki/Rain_gauge#Tipping_bucket_rain_gauge [4]: http://web.archive.org/web/20060110140456/http://www.met.tamu.edu/class/METAR/metar-pg9-ww.html#DRIZZLE [5]: https://web.archive.org/web/20180328124309/https://www.wunderground.com/weather/api/d/docs?d=resources/phrase-glossary&MR=1 [6]: https://www.wunderground.com/weather/api/d/docs?d=resources/phrase-glossary&MR=1 [7]: https://i.stack.imgur.com/iAm1S.png