China's national observatory on Monday issued a yellow alert for sandstorms in the northern part of the country. “    1    （start）from Monday to 8 a. m. Tuesday, affected by cold fronts and heavy winds, floating sand and dust       2    （expect）to sweep parts of several northern provinces and the city of Beijing,”     3    （forecast）the NMC.

Some regions in Inner Mongolia, Ningxia, Shaanxi and Shanxi were hit by strong sandstorms. The capital Beijing was enveloped in yellow dust     4     Monday morning with visibility at less than 1 km,     5     followed an official yellow warning for the sandstorm. The sandstorm is the strongest and the most sweeping     6     in nearly a decade. Remote sensing images of dust in northern China show the dust from Mongolia     7    （gradual）traveled south with the airflow.

This wave of sandstorms is a result of the combined       8    （effect）of cold air and cyclones from Mongolia. “The combined action of the Mongolian cyclone and the cold high     9    （press）provided a strong impetus（动力）for the sandstorm,” said Zhang Bihui,     10     senior engineer with the NMC.