A fallen tree rests atop a pickup truck in Holly Springs, Miss., after a storm struck the town on Wednesday. A storm system killed several people as it swept across the South. Phillip Lucas/AP hide caption

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Using an instrument they've named the HOLODEC, for Holographic Detector for Clouds, scientists can now see in fine detail the way air and water droplets mix at a cloud's wispiest edge. iStockphoto hide caption

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What's At The Edge Of A Cloud?
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A photo from May shows Gino Celli checking his parched crops near his farm near Stockton, Calif. If predictions of a strong El Niño prove true, it could presage a relief from the region's prolonged drought. Rich Pedroncelli/AP hide caption

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The National Hurricane Center introduced a new storm surge forecast map this year. This map, centered on New Orleans, is a prototype. NOAA hide caption

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10 Years Since Katrina: A Look Back At The Busiest Hurricane Season
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A lot of the airborne particles in the Earth's atmosphere come from natural sources, such as desert dust (red-orange) and sea salt (blue). But there's also soot from fires (green and yellow) and sulfur emissions (white) from burning fossil fuel. William Putman/ NASA/Goddard hide caption

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A partially frozen American Falls in sub-freezing temperatures is seen in Niagara Falls, Ontario, on Tuesday. Temperature dropped to 6 degrees Fahrenheit on Tuesday. The National Weather Service has issued a wind chill warning for western New York from midnight Wednesday to Friday. Lindsay DeDario/Reuters/Landov hide caption

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Pedestrians brave the cold during their morning commute on Friday in New York. Arctic air and bitterly cold wind is moving across the Northeast, plunging temperatures into record-low single digits, accompanied by subzero wind chills. John Minchillo/AP hide caption

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An Indonesian police officer in Kumai port in Pangkalan Bun carries part of a plane found floating on the water near the site where AirAsia Flight 8501 disappeared on Sunday. Achmad Ibrahim/AP hide caption

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The drought forced many citrus farmers near Orange Cove, Calif., to mulch their trees because they couldn't afford to keep them alive. Recent rain and new groundwater regulations have eased the crisis, but only slightly. Kirk Siegler/NPR hide caption

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Rain Eases California Drought Anxiety, If Not The Actual Drought
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Marina owner Mitzi Richards carries her granddaughter in September as they walk on their boat dock at the dried up lake bed of Huntington Lake in California, which was at only 30 percent capacity as a severe drought continued. The state was in the grip of its third year of severe drought, the worst in decades. Mark Ralston/AFP/Getty Images hide caption

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