Fires in the floodplain of the Parana River in Argentina spilled thick smoke over the nation’s capital in mid-April 2008. This image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite was captured on April 20, a day when winds were pushing the smoke south, rather than southeast over Buenos Aires. Places where MODIS detected active fires are outlined in red. Small clouds, known as “popcorn cumulus,” are scattered over the left side of the image. According to news reports, the fires were set by farmers clearing pasture for cattle. The amount of burning may have been exceptionally large because former pastures are now being used to grow soybeans, according to a news report from Bloomberg.com citing Argentina’s Interior Minister. The smoke interrupted road and air traffic, and sent many people to hospitals with respiratory distress.