Sydney Morning Herald: The devastating Russian heatwave and Pakistan floods are caused by one unusual weather pattern – the static jet stream, meteorologists say. The northern hemisphere jet stream, a fast-moving high-altitude air current, circles the earth from west to east. But in the past month, a “blocking event” has brought the jet stream to a halt, keeping weather patterns stationery over certain countries. A US helicopter takes supplies to flood victims in Kalam, Pakistan. Photo: …