Think of a Jet stream as a fast-moving river of air. It is generally defined by wind speeds of 50 knots or greater with the strongest wind contained in the core of the jet stream. They form along boundaries between hot and cold air. Since these hot and cold air boundaries are most pronounced in winter, jet streams are the strongest and farther south during the winter. That also means jet streams are weaker and farther north in the summertime. Troughs will most likely have clear air turbulence as

2022年10月 JAL機内版 JET STREAM【ジェットストリーム】（福山雅治）