1.   Cloudy skies obscured visibility and temporarily grounded the state-of-the-art prototype.

2.   Dirty screens can also obscure visibility and restrict air flow.

3.   The agency is studying whether emissions are obscuring visibility at Big Bend, Rueda said.

4.   The conditions obscured visibility on a race course that featured steep, rock-strewn trails hugging precipitous cliffs and primitive bridges traversing swift, glacial rivers.

5.   A supertanker rammed into the Indian-registered cargo ship late Friday night in the Strait of Malacca, where thick smoke from forest fires obscured visibility.

6.   U.S. jets could be heard over the Shomali plain north of Kabul, but clouds of dust covered the area, obscuring visibility.

7.   Snow moved in briefly during the first-leg, obscuring visibility.

8.   Snow moved in briefly during the first leg, obscuring visibility.