Usually,this requires near-freezing temperatures, light winds and changing conditions in Earth's atmosphere.

VOA: special.2011.01.11

He said just as the terrorists adapt to changing conditions, so will the United States.

VOA: standard.2010.01.05

"Whiteface is super steep. And it has ever-changing conditions."

VOA: standard.2010.02.09

Survival means changing as conditions change.

VOA: special.2009.04.20

"We are working on a grassroots level to identify the issues that are going on in the community, and developing and cultivating leaders to take charge of their own communities and really changing the conditions that they find themselves in.

VOA: standard.2010.02.24