Hitting The Hot Spots
Scientists attending a recent American Geophysical Union meeting reported on a new lightning detection network that helps predict storms and pinpoint “hot spots” of lightning activity. Comparing two years of human observations of thunderstorms to data collected from a network of magnetic lightning detectors, Ronald Reap of the National Weather Service’s Techniques Development Laboratory, Silver Spring, Md., found that the magnetic detectors identify three to four times as many thunderstorms as the human observers do. The magnetic detectors in the network he studied use small antennae to sense electromagnetic waves created when lightning disturbs Earth’s magnetic field. Researchers are using the improved detection capability to assist in forecasting severe storms and to map “lightning climatologies,” the distribution of lightning over geographic areas. The detectors are especially useful for locating developing thunderstorms obscured by other meteorological activity Such information helps scientists to understand exactly what occurs in thunderstorms, to plot cycles of storm growth and decay, and to identify areas with high density of lightning—information that could be valuable in, for example, urban planning.
It’s shaped like a hockey puck but is less than one-tenth the thickness of a human hair on a side. What is it? A new kind of semiconductor laser that has possible applications ranging from optical computing to improved optical telecommunications. The microscopic laser is a custom-tailored single crystal with mirrors and lasing medium precisely grown layer by layer—by molecular beam epitaxy—in the laboratory. Last month, scientists at Sandia National Laboratories, Albuquerque, N-Mex., announced that they had, for the first time, demonstrated high-efficiency, continuous-wave, room-temperature operation in epitaxial surface-emitting laser structures. "We have a surface-emitting laser that is very efficient and operates continuously at room temperature, “says Paul L Gourley, the Sandia physicist who heads the research effort. “This at least matches previous semiconductor lasers. But it has the advantage that the light comes out of the surface, and it has a very well-defined, circular beam.”