Behind the Forecast: How the jet stream affects weather and flight times

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Published: Sep. 4, 2020 at 9:34 AM EDT
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LOUISVILLE, Ky. (WAVE) - Wind whizzing by at more than 100 miles per hour overhead plays a significant role in weather patterns worldwide.

That whizzing wind is the jet stream: a narrow band of strong wind in the upper levels of the atmosphere that blows from west to east across the planet. Our planet has four primary jetstreams: two subtropical jets near the equator and two polar jets near the south and north poles.

The reason for all this wind? Air masses of differing temperatures. When cold and warm air masses meet, warmer air rises through the atmosphere while cold air sinks to take its place, creating wind. Significant differences in temperature, like those seen during the Winter, can lead to stronger winds.

On average, a jet stream travels at around 110 miles per hour. If the temperature difference is large enough, wind speeds can exceed 250 miles per hour. The polar jet stream could see speeds that fast during the Winter.

Jet streams transport weather systems across the globe, influencing wind, precipitation, and temperature patterns. If a system develops or moves away from a jet stream, the weather pattern may remain stagnant in that region. While jet streams mainly transport weather systems from west to east, dips and rises in latitude and altitude in them can push systems north and south. High and low-pressure systems can also influence where a jet stream is located.

Jet streams are much like sunflowers because they follow the sun. As the sun’s elevation increases during the Spring, the jet stream inches towards the poles. In the Fall, the jet stream’s average latitude sinks south as the sun’s elevation decreases.

Jet streams are so helpful in air travel. The jet stream sits in the mid to upper troposphere; this is about five to nine miles up at levels where planes fly. The strong winds of the jet stream can provide a boost of speed for aircraft traveling from west to east, cutting down travel time.

Satellites like the Geostationary Operational Environmental Satellites-R Series (GOES-R) help meteorologists and other scientists detect a jet stream’s location by using infrared radiation to detect water vapor in the atmosphere.

Tracking where a jet stream is located can help meteorologists figure out where weather systems can go next.

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