The jet stream is a powerful, high-altitude wind current that flows from west to east in the Earth’s atmosphere. These narrow bands of air are located near the tropopause, the boundary between the troposphere and the stratosphere, and often travel at speeds exceeding 100 miles per hour. They play a significant role in steering weather systems and influencing global travel patterns. The history of this atmospheric phenomenon involves gradual theoretical understanding, an abrupt practical realization, and formal scientific definition.
Early Theoretical Concepts
The concept of a powerful, eastward-flowing current high in the atmosphere was first hypothesized in the mid-19th century. American professor Elias Loomis proposed the existence of a strong upper-air current over the United States to explain the movement of major storms. This early idea suggested that a large-scale atmospheric circulation pattern was at work, a precursor to the modern understanding of thermal winds.
Isolated observations followed in the early 20th century. Japanese meteorologist Wasaburo Oishi conducted experiments in the 1920s using weather balloons launched near Mount Fuji. His meticulous tracking data allowed him to detect and measure these high-speed winds, confirming the existence of a major atmospheric river.
Oishi’s findings, however, were published in Esperanto and remained largely unknown to the Western scientific community. Separately, in the 1930s, American aviator Wiley Post observed a strange discrepancy between his ground speed and air speed during high-altitude flights. This suggested a very strong, unseen current was propelling his aircraft. The term “jet stream” was first officially used in 1939 by German meteorologist H. Seilkopf, based on pilot reports and theory.
The Sudden Discovery During World War II
The true realization of the jet stream’s power came not through planned scientific research but through the unexpected operational challenges of military aviation. The introduction of high-altitude bombers during World War II forced aircrews to fly at altitudes where the existence of such a powerful wind current became impossible to ignore. This realization began in earnest with the U.S. Army Air Force’s B-29 Superfortress bombing raids over Japan, which began in late 1944.
These aircraft, designed for precision bombing at altitudes up to 30,000 feet, suddenly encountered winds of unprecedented strength. Pilots reported winds gusting up to 200 miles per hour, and sometimes exceeding 300 miles per hour. The winds were so powerful that they could drastically increase the ground speed of a bomber heading east, causing it to overshoot its target by miles, or slow a westbound bomber to a near-standstill.
The intense encounters severely compromised the B-29s’ mission effectiveness, burning fuel at alarming rates and making accurate bombing impossible. This practical discovery provided the Western Allies with a wealth of new, firsthand data about the speed, altitude, and location of the upper-level flow. Military reports from these Pacific missions became the first large-scale, documented evidence of the jet stream’s presence.
Mapping and Naming the Atmospheric River
The immediate post-war era saw the scientific community rapidly synthesize the military’s shock reports into a formal meteorological model. The vast amount of data collected from the B-29 flights provided the concrete measurements necessary to map the phenomenon. Swedish-American meteorologist Carl-Gustaf Rossby became instrumental in this formalization.
Rossby had already developed the theoretical framework for large-scale atmospheric waves that govern the flow of the upper-level air. He and his team at the University of Chicago used this new data to define the structure and dynamics of the powerful currents. They formally integrated the concept into atmospheric science, helping to establish the link between the high-altitude flow and surface weather systems.
Rossby’s work in the late 1940s cemented the concept and popularized the name “jet stream” within the global scientific lexicon. This formal identification and mapping effort quickly revolutionized both meteorology and aviation. By the early 1950s, the jet stream’s structure was well-defined, allowing for its integration into modern weather forecasting and flight planning.
The knowledge gained from wartime necessity transformed into a scientific breakthrough. This enabled commercial airlines to use the powerful tailwinds to shorten flight times and save fuel on transcontinental routes.