Jet stream

Structure and causes

The principal drivers of jet streams are horizontal temperature gradients and the rotation of the planet. Warm and cold air masses set up pressure differences; the Coriolis effect turns the resulting winds into narrow, high-speed currents. Two major types are commonly identified: the polar jet, found at higher latitudes, and the subtropical jet, nearer the tropics. Important characteristics include strong wind shear, meandering paths, and vertical depth often confined to a few kilometres.

Characteristics and effects

• Speed: Wind speeds within jet streams can exceed 100 m/s in extreme cases, but vary widely.
• Shape: They often form sinuous waves called Rossby waves, which influence the position of weather systems.
• Weather influence: Jet streams steer storms and frontal systems and modulate precipitation and temperature patterns.

Uses and practical importance

Jet streams are vital to meteorology and aviation. Forecasting models use their position and strength to predict storm tracks and surface weather. Airlines plan routes to take advantage of tailwinds or avoid headwinds to save fuel and time. In climate studies, shifts in jet streams are monitored because they can affect regional droughts, heat waves and cold outbreaks.

History, research and notable facts

Knowledge of jet streams developed during the 20th century, accelerated by high-altitude flight and balloon observations. Research continues into how jet streams respond to natural variability and long-term changes; scientists study links with phenomena such as sudden stratospheric warming and how altered temperature gradients can change jet positions. For introductory references on atmospheric layers and temperature structure see the entries for the troposphere, stratosphere and general temperature profile.