Find out how each NAO phase spins its particular brand of atmospheric tumult, affecting temperature, precipitation, cloudiness, and windiness in different regions — sometimes to drastic ends.

From the chilly depths of the Atlantic to ancient European forests, researchers are combing for data to explain the NAO's mysteries.

Northern Hemispheric temperatures are now at their steamiest. Discover why scientists are concerned about global warming's potential backlash on the NAO.

Where would the world be without oxygen? While it's hard to imagine an Earth without it, for nearly the first half of the planet's 4.5-billion-year history, Earth had no oxygen gas as part of its atmosphere.

Where would the world be without oxygen? While it's hard to imagine an Earth without it, for nearly the first half of the planet's 4.5-billion-year history, Earth had no oxygen gas as part of its atmosphere.

One of the biggest forces that's shaped planet Earth over time is microscopic in size. Explore the global impact of microbes.

Earth's early atmosphere disappeared eons ago. So how does a present-day scientist go about studying it?

In 1669, the fastest and largest lava flow documented for Mount Etna on the island of Sicily killed most of Catania's 20,000 residents and destroyed much of the city. Why are scientists now watching Etna more than any other volcano in Europe? Find out.

Long ago, people studied jellies by peering over the side of a boat and drawing the creatures as they bobbed nearby. See how much has changed since the 1800s.

From the Great Blizzard of 1888 to the sinking of the Titanic, see how NAO may have affected history. Then look at how it may affect the future.