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NASA (Liam Gumley at the
Wildfires are Burning in the Western United States
News story originally written on June 14, 2002
There are 19 large wildfires burning over 550,000 acres in the United States (as of June 13, 2002). Most of the fires are within western states such as California, Utah, Colorado, New Mexico, Wyoming and Alaska.
The largest fire, called the Hayman fire, has burnt almost 100,000 acres southwest of Denver, Colorado since Sunday June 9, 2002. Colorado has not received the typical amount of rain and snow this year, making the pine and conifer forests very dry and easily burnt. Although it has burnt some homes, the fire is mostly in National Forest land. A campfire started the blaze even though there is a ban on campfires in the area.
Wildfires may be started by either human or natural causes. Some wildfires are started naturally, usually sparked by lightning strikes. People who handle fire carelessly, however, start other wildfires. In Colorado this spring, people have accidentally started wildfires by dropping lit cigarettes on the ground, starting campfires in very dry conditions, and from letting a barbeque grill overturn.
A fire needs three things to burn: fuel, oxygen and heat. In the case of a wildfire, the fuel is trees, grasses, and shrubs, especially those that are dead and dry. The oxygen needed for a fire to burn comes from the air in our atmosphere, which contains approximately 21% oxygen. Heat is also necessary and temperatures of about 617 degrees F (325 degrees C) are needed for wood to burn. To stop a wildfire, firefighters try to take one or more of these three things from the fire.
The wildfires in the Western United States are being fought by a variety of methods. They are fought on the ground by firefighters with special training who attempt to smother the fire by covering it with dirt (removing oxygen) or water (removing heat). They also try to contain the fire by removing the dry wood that fuels it. Fires are also fought from the air with planes dropping a soupy material called slurry onto fires from above, separating the fire from oxygen. Additionally, NASA's Terra satellite is helping scientists and land managers to monitor fires from space by producing images like the one on the left that shows the location and extent of fires.
Despite efforts to stop wildfires, they are often natural occurrences started by lightning strikes. Small natural wildfires, called low intensity fires, can even be beneficial to forests, since they clear underbrush and dead trees, and make room for larger, living trees. This season's large wildfires in the West, however, have been high intensity fires, which destroy entire forests and do not benefit the environment. They burn both living and dead trees, with flames reaching the tops of the trees and jumping from one tree to another.
