Atmosphere

atmosphere

Carbon tet still offensive to ozone layer

Earth’s ultraviolet light-shielding ozone layer is recovering, according to a report released in September by the World Meteorological Organization and the United Nations Environment Programme. The findings, authored by more than 250 scientists and presented as part of the latest Scientific Assessment of Ozone Depletion (SAOD), suggest the ongoing success of the 1987 Montreal Protocol and its amendments in cutting atmospheric levels of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS’s), which have fallen by about 10 to 15 percent overall since peaking in the late 1990s.

22 Dec 2014

The Chesapeake Bay gets some good news

The Chesapeake Bay watershed is the largest on the Atlantic seaboard, encompassing most of Maryland and Virginia, along with parts of Delaware, New York, Pennsylvania and West Virginia. More than 150 rivers flow into the system, carrying pollution and nutrient runoff from a 160,000-square-kilometer area into the bay ecosystem. A new study tracking long-term effects of the Clean Air Act has some good news about the often-poor water quality in some areas of the Chesapeake Bay watershed, but the overall picture may be complicated by hydrology.

02 Apr 2014

Still in a haze: What we don't know about black carbon

Black carbon — fine particles of soot in the atmosphere produced from the burning of fossil fuels or biomass — has been known to be a health hazard for decades, a major contributor to the thick hazes of pollution hovering over cities around the world.

14 Mar 2011

Greening the friendly skies

If you’re a frequent flyer, the script of plane travel is probably so familiar you may mumble it along with the flight attendant: “Please raise your tray tables and return your seatbacks to their full upright position. We’re beginning our descent.” The sounds of that descent are probably just as familiar: The whir of landing gear descending, the loud drone of engine power rising and falling as the plane makes a series of stair-step descents to lower and lower altitudes before landing on the runway.

02 Nov 2010

Crystal Ball EARTH: Space: NASA keeps watch on a changing planet

In 2009, we saw a number of changes on Earth. The average global ocean surface temperature last summer was the warmest on record. Thin seasonal ice has recently replaced thick older ice as the dominant type of ice in the Arctic. And scientists saw that despite a quiet sun with few sunspots, Earth can continue to be bombarded with a high level of solar energy.

11 Dec 2009

Benchmarks: September 16, 1987: Montreal Protocol Signed

Each year in late September to early October, atmospheric scientists watch with anticipation as ozone concentrations over Antarctica drop, opening a window in Earth’s defenses against harmful ultraviolet radiation. This ozone “hole” grew steadily in the 1990s and set a record for its size in 2006: At its peak, the hole covered an average area of 27 million square kilometers, approximately the size of North America. But scientists think that the overall ozone layer is on the slow road to recovery, thanks to the Montreal Protocol — one of the most successful international environmental agreements in history.
 
16 Sep 2009

Air pollutants from "megacities" a growing problem

Megacities — cities with populations equaling or greater than 10 million people — are producing an unprecedented amount of air pollution, according to scientists at the American Chemical Society's annual meeting in Washington, D.C., on Tuesday.

21 Aug 2009

Raindrop study splashes old assumptions

Predicting the weather has been central to human civilization since the Babylonians started studying cloud patterns in 650 B.C. The key to weather predictions is making correct assumptions. Today, instruments like Doppler radar that measure rainfall work under the assumption that raindrops fall at their terminal velocity. A new study, however, shows that some raindrops fall faster than they should, indicating rainfall instruments — and by extension, weather forecasts — may need some tweaking.

23 Jul 2009

Montreal Protocol affects more than just ozone

In 1987, nearly 200 nations signed the Montreal Protocol to restrict the use of ozone-depleting chemicals. The international treaty helped keep the ozone hole over Antarctica from growing further, preventing an increase in harmful radiation reaching Earth’s surface. Twenty years later, new research suggests that the treaty helped the planet dodge more than one bullet: The Montreal Protocol also prevented significant regional climate change.

13 Nov 2008

Pages