and reduce visibility for days over areas the size of Britain. 所到之处能见度骤降为零 几天内横扫的地区比英国还大

50. It's the size of the United States
    它的面积相当于美国
51. and the biggest source of sand and dust in the entire world.
    也是全世界最大的沙尘源
52. Sandstorms like these appear without warning
    如此巨大的沙暴出现时毫无征兆
53. and reduce visibility for days over areas the size of Britain.
    所到之处能见度骤降为零 几天内横扫的地区比英国还大
54. Dromedaries, single-humped camels, take these storms in their stride.
    单峰驼——只有一个肉峰的骆驼 顶着沙暴大步行走
55. The heaviest sand rises only a few metres above the ground,
    最重的沙子只能离开地面几米
56. but the dust can be blown 5,000 metres up into the sky.
    但是尘埃却能被吹上5000多米高的天空

来自《行星地球 第一季 第五集 Planet Earth S01E05 沙漠》第 53 行