What's a Jet Stream?

It’s a fast–moving current of air that circulates around the Earth in a corkscrew motion at altitudes of 25,000 to 45,000 feet. A jet stream’s speed and momentum are affected by the varying temperatures in the southern and northern latitudes as well as by the Earth’s rotation. Average high speeds are between 150 and 180 knots. The force of a jet stream often leads to quicker flight times by creating what pilots refer to as “push.” A flight from Toronto to Vancouver can take five hours, but with the effect of a jet stream, the return trip can be reduced by 40 minutes.