By Syndicated Content By Rich McKay (Reuters) – Scores of wildfires raging across the Western United States’ forest and scrub have belched so much smoke that it is helping an army of firefighters gain ground on the nation’s biggest blaze, Oregon’s Bootleg fire, by blocking sunlight, officials said on Saturday. Both the National Weather Service and officials with the Oregon Department of Forestry said smoke in the lower atmosphere coming from California wildfires has floated over the Bootleg fire, which has scorched more than 401,000 acres in Oregon about 250 miles (402 km) south of Portland. “It’s called ‘smoke shading’ and it’s basically put a lid on the lower atmosphere for now, blocking sunlight and creating cooler, more stable surface conditions,” said Eric Schoening, a meteorologist with the National Weather Service in Salt Lake City.