What is the relation between wind speed and the spacing of isobars?
relate the jet-stream phenomenon to general upper-air circulation. how is the presence of this circulation related to airline schedules from new york to san francisco and the return trip to new york?

Relation as explained below.

Explanation:

When the isobars are far the winds are weak and when they are close the winds are stronger as iso-bars represent the same pressure and wind systems found on earth's surface. So the spacing shows the strong pressure difference.  The jetstreams are narrow bands of winds that develop mostly in winters these jet streams move in an eastern direction following the movement of pressure ridges in upper air circulation. Polar jets are found at 9 to 12 km i.e 30,000 to 40,000 feet above mean sea level. The path followed by the new york flight to San Francisco and a return back to new york is the same path followed by the jets as they are greater where the temperatures difference are greatest and winds speeds can go up to 400 km/hr.  As the jet moves from west to east bringing changes to weather the flight is delayed so that turbulences don't hamper or hinder the flight path. The Coriolis force is also responsible for the movements in upper air circulation.

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