Enhancement of Surface Cooling Due to Forest Fire Smoke

Smoke emitted from forest fires in northern California in September 1987 was trapped in a valley by an inversion for 3 weeks. Daily maximum temperatures on the valley floor were more than 15°C below normal for 1 week and more than 5°C below normal for 3 weeks. The smoke strengthened the inversion by preventing surface warming by solar radiation, thereby enhancing the smoke trapping and the surface cooling in a positive feedback loop. These results may have implications for nuclear winter.