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
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.
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.
NOAA's GOES-East satellite provided a look at the frigid eastern two-thirds of the U.S. on Wednesday that shows a blanket of northern snow, lake-effect snow from the Great Lakes and clouds behind the Arctic cold front.
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.
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.