Wildfires
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite took this image at 12:35 p.m. local time on May 16. Similar images of central Canada are available twice daily.
The top view shows a wide area to illustrate how far the smoke traveled. The lower image provides a closer view of a massive fire burning south of Lake Athabasca. Fire detections are outlined in red. Strong winds fanned the fires on May 15 and 16, pulling thick plumes of smoke north.

A forest fire is seen in California 2009. A wildfire engulfed the town of Slave Lake in western Canada, forcing the evacuation of its 7,000 residents at the start of the forest fire season, authorities said Monday
Dozens of forest fires flared up across the province during a dry, gusty weekend, forcing the evacuation of several communities, including Slave Lake, a town of 10,000 people in northern Alberta known as a center for oil, gas and forestry.
Numerous homes and some public buildings had been razed in Slave Lake, Mayor Karina Pillay-Kinnee said.
She spoke to reporters from a command center in the town, about 200 km (125 miles) northwest of the provincial capital, Edmonton. It was deserted save for emergency personnel.
"You feel the intense heat, the sharp smell of smoke ... you see some areas still smoking and our fire-fighting crews are trying to contain any spot fires," Pillay-Kinnee said.
Two blazes, driven by winds gusting to 100 km per hour (60 miles per hour), converged on Slave Lake on Sunday. Complicating the situation on Monday were winds up to 50 km per hour (30 mph) in some regions as well as dry conditions.
Nearly a third of the buildings in Slave Lake were destroyed Sunday after strong winds suddenly turned the flames towards the town in Alberta Province, police said.
All residents were ordered to leave Sunday afternoon, but evacuation proved difficult as smoke and fast-moving flames blocked some of the highways. By Monday, however, 90 percent of residents were said to have fled.
"It was certainly a surreal experience seeing the flames against the night sky," Geoffrey Driscoll was quoted by the Calgary Herald as saying. "We could see behind us parts of the town on fire."

The Town of Slave Lake has declared a state of emergency as wildfires force 260 people from their homes
Close to 1,000 people have been forced from their homes since the fires broke out Saturday afternoon. Initially, about 260 people were evacuated from the Poplar Lane and Mitsue areas but Sunday afternoon, another 700 residents were ordered out of the area because of another fire burning southwest of the community.
Displaced residents are being sent to a Red Cross reception centre at Northern Lakes College. Two schools in the area are being set up as temporary shelters for evacuees.
Sonny Stiger, a fire behavior analyst, told a group gathered in Helena Wednesday for a forum on the impact of the rice-size beetles, that he's seeing flame lengths of 200 to 300 feet in places they wouldn't expect it; they're experiencing unusual embers being thrown farther ahead of fires and groups of treetops torching; and ponderosa pines' low-hanging dead branches are creating ladder fuels that allow blazes to spread more rapidly than in the past.
"The kind of things we're dealing with is one fire grew to three acres in two minutes, 10 to 15 acres in the next eight minutes - that's moving - and over 100 acres in the first hour," Stiger said. "So we are experiencing unusual, extreme fire behavior now."
During the past decade, mountain pine beetles have devoured about 9 million acres of forest in the Rocky Mountains from Colorado to Montana, and about 40 million acres in British Columbia. They kill mainly lodgepole and ponderosa pine trees by burrowing into them to lay eggs; when the eggs hatch, the young "girdle" the tree by eating around it in horizontal circles, cutting off the flow of nutrients, before they fly to new trees and re-create the deadly cycle.

Texas Gov. Rick Perry takes a break from making photos to look at an area burned by wildfires from a jet plane during a low altitude tour of Stonewall County near Swenson, Texas, Tuesday, April 12, 2011.
Strong winds and drought-stricken grasses and shrubs are fueling the fires that forced hundreds of evacuations, including an entire town, and destroyed at least 60 homes on Friday. Firefighters worked overnight as the blazes burned across about 655 sq. miles, according to the Texas Forest Service.
Some of the fires have been burning for a week or more, including three in West Texas that have charred a combined 400,000 acres.
Volunteer firefighter Gregory M. Simmons, 51, died while battling a 3,000-acre blaze Friday afternoon near Eastland, a town about 130 miles west of Dallas, Eastland Mayor Mark Pipkin said. Simmons had been a firefighter for two decades, including 11 years in Eastland, the mayor said.
"Apparently he was overcome by smoke, fell in a ditch and was consumed" by the fire, said Justice of the Peace James King, who pronounced Simmons dead at the scene along a rural road.
No other injuries have been reported.

NASA Earth Observatory image created by Jesse Allen, using Landsat 5 data provided by the United States Geological Survey.
The fires, called El Bonito and La Sabina, were caused by lightning strikes in mid-March and had burned 99,000 hectares (245,000 acres or 380 square miles) as of April 11. The fires are among the largest in Mexico's history, according to news reports. The burned land is brick red in the lower image. Hot areas glow orange in infrared light, revealing the active fire front on the south and west sides of the burned area. (The orange horizontal stripes are satellite sensor artifacts.)
The Texas Forest Service reported more than 60,000 acres burned and 40 homes lost in one blaze that raced through West Texas and into the small mountain town of Fort Davis. The fire rushed across 20 miles in 90 minutes.
Officials at the scene, however, estimated at least 100,000 acres in two counties had burned from the fire, which continued to grow Sunday evening.
"I can only describe it as an ocean of black, with a few islands of yellow," State Representative Pete Gallego said.
Deputy Michelle Rademacher of the Douglas County Sheriff's Office said the latest fire has scorched about 1,600 acres in the wooded bluffs near Franktown, Colorado.
"We're not aware of any structures lost, but the high winds are pushing it close to heavily populated neighborhoods, so we called for mandatory evacuations," she said.
The fire grew quickly as sustained winds of 40 miles per hour fanned the flames through dry brush, grasses and trees.