Q: I’ve heard lightning rarely strikes in the Arctic. Why is that?
— Carter Matthew | Boston
For thunderstorms and resultant lightning to occur, there must be rising currents of warm, moist air. Deep in the Arctic and Antarctic, there is only cold, dry air, which does not rise, and thus cannot form thunder clouds, says Douglas Herman, senior geographer at the National Museum of the American Indian. But as climate change brings moister, warmer air to the area, lightning is increasing and causing fires in the boreal forests where that used to be rare.
Q: My barber sends hair clippings to organizations that use them to soak up oil spills. Does that work? What other tricks are used?
— Claire Bugos | Evanston, Illinois
The most common methods for cleaning up oil spills are dispersing, in situ burning or skimming. Chemical dispersants break up the oil slick into droplets, which mix into the water column or are broken down by microbes. That option, used in the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, can be harmful to marine life, says Andrea M. Quattrini, research zoologist and curator of anthozoa at the National Museum of Natural History. For the other approaches, a boom first concentrates the spill in one area. The oil is either set on fire, or is removed from the surface using a device called a skimmer. There are different designs and methods, including using suction or gravity to move the oil in storage tanks. Hair clippings can be used to make the containment booms, but are not widely deployed.
Q: How does a coffee brand earn the label “bird-friendly”?
Coffee plants can be grown either in the understory of tree canopies, a practice that helps sustain migratory bird habitat, or in direct sunlight, which drives deforestation and leads to less diverse habitats. To conserve habitats for overwintering migratory bird populations, Smithsonian’s Bird Friendly certification effort, started in the late ’90s, supports farmers who opt for shade-grown coffee, says Scott Sillett, who heads the Smithsonian Migratory Bird Center. At the moment, 45 farms are participating in the program, primarily in Central and South America. To be certified, a plantation must include forest land that has not been cut for at least ten years, support ten native tree species, provide 40 percent shade coverage and also be USDA-certified organic.
Q: Will climate change have any effect on all the “space junk”—like outdated satellites or spent rocket stages—currently in orbit?
— Don Maddox | Pasadena, California
When scientists discuss the greenhouse effect, they’re usually talking about changes in the troposphere, the lowest part of Earth’s atmosphere. The thermosphere, where most of these man-made orbiting objects are located, is also experiencing an increase in carbon dioxide. But at that level, because the atmosphere is much less dense, carbon dioxide behaves differently, says Martin Collins, curator of the civilian applications satellites collection at the National Air and Space Museum. Instead of trapping heat, the CO2 releases heat into space and chills this upper layer of atmosphere. As a consequence, the thermosphere contracts, resulting in less atmospheric drag or friction on such objects.
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