The deadly heat waves that have fueled blazes and caused transport disruptions in Europe, the U.S. and China this month have one thing in common: a peculiar shape in the jet stream dubbed “wavenumber 5.” Scientists are racing to understand whether the band of fast-moving air that controls weather in the mid-latitudes is changing in a way that makes heat waves more frequent and persistent. “The jet stream is the leading driver of our weather,” said Paul Williams, professor of atmospheric science at the University of Reading in the U.K. “The jet stream is like a conveyor belt, delivering storms to us one after the other.” It […]