Jet Stream

Jet Streams are fast flowing, narrow air currents found in the upper atmosphere, located near the tropopause. The strongest jet streams are the polar jets, at around 7-12 km (23,000-39,000 ft) and the subtropical jets at around 10-16 km (33,000-52,000 ft). The wind speed varies according to the temperature gradient, exceeding 92 kilometers per hour (50 knots) although speeds on the order of 398 kilometer per hour (215 knots) can occur. Jets steams steers cyclonic systems, or low pressure systems, at lower levels in the atmosphere, thus, knowledge of their course has become an important part of weather forecasting.

Sources:American Meteorological Society. 2013. Glossary of meteorology. Accessed on 11 September 2013. Available at National Wildfire Coordinating Group Smoke Committee. 2011.