This brings us to the end of the module! We started by discussing why Air India changed its Delhi-San Francisco route, adding around 1,400 kilometres to the journey? We had asked if Air India did it to set a record. Of course not! The answer is jet streams. Jet streams are very fast moving air currents (speeds often exceed 100 km/h) that occur very high in the atmosphere. Because the Earth rotates from West to East, many jet streams tend to move in the Eastwards direction.
Even though the distance covered by the new Air India route was more, because the aeroplane was moving in the direction of the jet stream, the travel time actually reduced by two hours! Basically, the fast moving air in the jet streams helped the airplane move faster, and even though the distance was more, the faster speed meant that the time required was less.