Standing 1.5 metres (4.9 feet) tall and roughly the size of a single-door refrigerator, the caesium atomic fountain clock can be loaded onto a military truck and, after enduring long-distance ...

Their goal is twofold: Get a baseline measurement of what the earth’s stratosphere looks like, and see how natural events such as volcanic eruptions and wildfires can change it. With that data ...

The eruption was one of the most powerful of the 19th century, spewing so much sulfur dioxide into the stratosphere that annual average temperatures in the Northern Hemisphere dropped by about one ...