Jet stream

The jet stream is a narrow band of strong westerly winds in the upper troposphere, driven by the temperature gradient between the equator and the poles. It is the atmosphere's primary mechanism for transporting heat and momentum from the tropics toward the poles, and its position and intensity govern the storm tracks that dominate mid-latitude weather. The jet stream is not a fixed geographical feature but a dynamical structure that shifts in response to changes in the Pacific Decadal Oscillation, the North Atlantic Oscillation, and other climate modes. From a systems perspective, the jet stream is the atmosphere's principal channel for resolving temperature gradients that would otherwise grow unstable.