Earth’s sky-high generator
The ionosphere is like a sloshing sea of electrically charged particles, created by the Sun and intermixed with the neutral upper atmosphere. Sandwiched between Earth and space, the ionosphere responds to changes from both the Sun above and Earth below. How much influence comes from each side is what researchers are interested in figuring out. Studying a year of ICON data, the researchers found much of the change they observed originated in the lower atmosphere.
Generators work by repeatedly moving an electricity-carrying conductor — like a copper wire — through a magnetic field. Filled with electrically charged gases called plasma, the ionosphere acts like a wire, or rather, a tangled mess of wires: Electricity flows right through. Like the dynamo in Earth’s core, the dynamo in the atmosphere produces electromagnetic fields from motion.
Strong winds in the thermosphere, a layer of the upper atmosphere known for its high temperatures, push current-carrying plasma in the ionosphere across invisible magnetic field lines that arc around Earth like an onion. The wind tends to push on chunky, positively charged particles more than small, negatively charged electrons. “You get pluses moving differently than minuses,” said co-author Brian Harding, a physicist at University of California, Berkeley. “That’s an electric current.”