And right back here at home there are two pictures that say so much about the incredibly brave and exhausted firefighters near yosemite national park. The wind is whipping the flames above the see coy... See More
And right back here at home there are two pictures that say so much about the incredibly brave and exhausted firefighters near yosemite national park. The wind is whipping the flames above the see coy ya trees and they are treasures, some of the oldest living things on earth. More than 3,000 men and women are inside the flames where the heat can reach more than 800 degrees. Abc's neal karlinsky is in the heart of the battle. Reporter: Along the edge of yosemite, a fire now so fierce it's creating its own weather patterns, so called thunderous cumulus clouds, big enough to be seen from space that can alter the wind direction rapidly and trap firefighters. We have had up to 43,000 quick flums plumes. That creates its own weather. This reservoir supplies up to 85 percent of san francisco's water and is being polluted by falling ash. The fire is being spread by crowning where the tops of trees torch, spreading faster than on the ground. Do you worried that any of these trees are going to come down while you are in there working? That's why we train the way we do with our eyes up. Reporter: More than 3500 are in this battle along the northeast, southwest and southeast, still 20 miles from el captain and other yosemite treasures. They dig up dry shrubs, bull dose the land and all to rob the biggest flames of more fuel. They also have small teams putting out spot fires that spring up. Here's one of the challenges. No fire here, blue sky and then all of a sudden, a spot fire breaks out. It's like this for miles up and down the road. Then there is this, a fire team deployed to protect three dozen of yosemites trees, some of the oldest living things on earth, in need of protection now. Neal karlinsky, abc news, yosemite national park.
This transcript has been automatically generated and may not be 100% accurate.