關(guān)于沙塵暴的英語作文 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，沙塵暴是指攜帶大量塵沙的風(fēng)暴，多發(fā)生在沙漠或半干旱地區(qū)。但科學(xué)意義上的沙塵暴卻有嚴(yán)格的指標(biāo)。氣象上一般以能見度來區(qū)分沙塵與沙塵暴：能見度小于1公里的為沙塵暴，能見度在1公里以上的為沙塵或揚(yáng)沙天氣。
中國環(huán)境檢測總站的專家們則以空氣中懸浮顆粒物的濃度作為衡量指標(biāo)。最近北京沙塵天氣時(shí)懸浮顆粒物濃度每立方米一般不超過1000微克，而沙塵暴時(shí)的濃度是要遠(yuǎn)遠(yuǎn)超過這個(gè)指標(biāo)的。
專家指出，應(yīng)該區(qū)分浮塵、揚(yáng)沙和沙塵等3種常見天氣情況。浮塵天氣時(shí)，大氣中彌漫細(xì)小顆粒物，灰塵多由外地而來，揚(yáng)沙天氣卷起的沙土則完全是本地產(chǎn)生的。沙塵天氣兼有浮塵和揚(yáng)沙兩種天氣情況，不過二者所占的比重有變化。沙塵天氣達(dá)到一定的指標(biāo)，才可稱作沙塵暴。