<br /> <p>A wildfire burning north of Santa Barbara on Saturday, August 20, sent huge plumes of smoke into the sky. The Rey Fire had spread over 21,000 acres</a> as of Sunday, three days after it started in the Los Padres National Forest. This timelapse video shows pyrocumulus clouds, or fire clouds, swirling above the blaze.</p><p>A pyrocumulus cloud is a dense cumuliform cloud formed by the intense heating of the air, caused by a wildfire or volcanic eruptions. Credit: YouTube/Jesse Rockwell</p><br />
