UPSC 2017 CDS I GK Paper

Statement (d) with regard to jet stream, an upper level tropospheric wave, is not correct. The jet stream consists of ribbons of very strong winds which move weather systems around the globe. Jet streams are found 9-16 km above the surface of the Earth, just below the tropopause, and can reach speeds of 200 mph. In winter (not in summer, as given in the fourth statement), the polar front jet achieves its maximum force.