Pyrocumulonimbus cloud formed by the firestorm following the atomic bombing of Hiroshima, 1945. Nuclear winter effects are triggered by at least a hundred such city firestorms.

Picture of a pyrocumulonimbus cloud taken from a commercial airliner cruising at about 10 km. In 2002, various sensing instruments detected 17 distinct pyrocumulonimbus cloud events in North America alone.

Smoke rising in Lochcarron, Scotland, is stopped by an overlying natural low-level inversion layer of warmer air (2006).

Diagram obtained by the CIA from the International Seminar on Nuclear War in Italy 1984. It depicts the findings of Soviet 3-D computer model research on nuclear winter from 1983, and although containing similar errors as earlier Western models, it was the first 3-D model of nuclear winter. (The three dimensions in the model are longitude, latitude and altitude.) The diagram shows the models predictions of global temperature changes after a global nuclear exchange. The top image shows effects after 40 days, the bottom after 243 days. A co-author was nuclear winter modelling pioneer

Artistic impression of an asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatán Peninsula in what is today Southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 66 million years ago, is believed to have caused the mass extinction of non-avian dinosaurs and many other species on Earth. The impact spewed hundreds of billions of tons of sulfur into the atmosphere, producing a worldwide blackout and freezing temperatures which persisted for at least a decade.