What causes California wildfires? Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07

What causes fires to spread? Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07

Southern California Is Mountainous Wpdms_shdrlfi020l_tehachapi_mountains.jpg (300 × 315 pixel, file size: 51 KB, MIME type: image/jpeg)Tehachapi Mountains ｩ 2004 Matthew Trump; Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
Subject to disclaimers. Downloaded from http://en.wikipedia.org/wiki/Image:Wpdms_shdrlfi020l_tehachapi_mountains.jpg on 10-27-07.

Hot air rises, fanning flames on mountain slopes.. NASA's Ikhana unmanned research aircraft flew over several of the Southern California wildfires Wednesday, Oct. 24, with its sophisticated thermal-infrared imaging equipment peering through smoke and haze to record high-quality imagery of the hot spots. The above 3-D images were taken at 10:21 a.m. PDT over the Harris Fire in San Diego County, looking west. The hot spots (in yellow) are concentrated on the ridgeline in the left center of the photo. Downloaded from: http://www.nasa.gov/vision/earth/lookingatearth/socal_wildfires_oct07.html on 10-27-07

Effect of Santa Ana Winds NASA photo shows smoke plume over Pacific caused by powerful Santa Ana winds in So Cal The winds fanned the fires and caused their rapid spread The latest NASA photo of the Southern California wildfires, above, is nothing short of breathtaking ... and not in a good way.The red pixels represent fire activity.Worse yet, this photo was taken on Tuesday at 2:25 p.m. Eastern Time, well before fire officials began to speak of hope that changing weather conditions might bring some relief.According to the space agency: "NASA satellites have obtained new images of the California wildfires, illustrating the immense scale of the blazes. The National Interagency Fire Center reports that 12 large, uncontained fires have burned over 335,000 acres in Southern California. The fires have continued to spread due to the fierce, dry Santa Ana winds.” Downloaded from: http://www.nasa.gov/vision/earth/lookingatearth/socal_wildfires_oct07.html on 10-27-07

What causes Santa Ana winds? High pressure area over the Great Basin Low pressure area over the Pacific Air from the high flows to the low The greater the difference between the high and the low, the stronger the winds Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07

Another Santa Ana Effect… As the high-altitude winds from the Great Basin sweep down the mountain slopes and descend to sea level, they warm up and dry out because of the increase in air pressure at that altitude. That's what makes the Santa Ana winds so withering. Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07

Why Are Some Years More Dangerous than Other Years? A wet spring causes lots of new brush to grow If a dry autumn follows, that leaves lots of dried brush to burn Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07

Human Life Choices Original people who lived in Los Angeles area, the Tongvas, called San Fernando Valley the “Valley of the Smokes.” To live successfully near the mountains, Californians must learn to exercise awareness of the natural environment. Photo downloaded from: http://tiffanyh.typepad.com/my_photo_blog/personal/index.html on 10/27/07