关于沙尘暴的英语作文 Sand Storm

　　In general, the sandstorm refers to carry large amounts of dust storm, tend to occur in the desert or semi-arid areas. But have strict scientific sense of the sandstorm. Weather in general with visibility to differentiate between the sand and dust storm: visibility less than 1 km to dust storms, visibility 1 km in more for dust or flying sand weather.

　　Experts with the China environmental testing station with the concentration of suspended particles in the air as a measure. Recently suspended particle concentration dust weather in Beijing general not more than 1000 micrograms per cubic metre, and dust concentration is far more than the index.

　　The expert points out, should distinguish between dust, flying sand and dust, etc. Three kinds of common weather conditions. Dust weather, diffuse tiny particles in the atmosphere, dust from outside, the flying sand weather of sand is local. Dust and flying sand dust weather with the two kinds of weather conditions, but the ratio of the two are changed. Dust weather as part of the index, can only be called a sandstorm.

　　一般而言，沙尘暴是指携带大量尘沙的风暴，多发生在沙漠或半干旱地区。但科学意义上的沙尘暴却有严格的指标。气象上一般以能见度来区分沙尘与沙尘暴：能见度小于1公里的为沙尘暴，能见度在1公里以上的为沙尘或扬沙天气。

　　中国环境检测总站的专家们则以空气中悬浮颗粒物的浓度作为衡量指标。最近北京沙尘天气时悬浮颗粒物浓度每立方米一般不超过1000微克，而沙尘暴时的浓度是要远远超过这个指标的。

　　专家指出，应该区分浮尘、扬沙和沙尘等3种常见天气情况。浮尘天气时，大气中弥漫细小颗粒物，灰尘多由外地而来，扬沙天气卷起的沙土则完全是本地产生的。沙尘天气兼有浮尘和扬沙两种天气情况，不过二者所占的比重有变化。沙尘天气达到一定的指标，才可称作沙尘暴。

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