Jet streams are like rivers of wind high above in the atmosphere. These slim strips of strong winds have a huge influence on climate, as they can push air masses around and affect weather patterns. The jet streams on Earth — other planets have jet streams as well, notably Jupiter and Saturn — typically run from west to east, and their width is relatively narrow compared to their length. Jet streams are typically active at 20,000 feet (6,100 meters) to 50,000 feet (9,144 meters), or about 7 miles (11 kilometers) above the surface and travel in what is known as the troposphere of Earth’s multi-layered atmosphere. While they are fairly narrow, they cover a wide latitude running north to south and often travel a very winding path; at times they can even fade away or break off into smaller “rivers” of air that merge again “downstream.”
The seasons of the year, location of low and high pressure systems and air temperature all affect when and where a jet stream travels. Jet streams form a border between hot and cold air. Because air temperature influences jet streams, they are more active in the winter when there are wider ranges of temperatures between the competing Arctic and tropic air masses.
How do temperatures affect the Jet Stream?
The greater the difference in air temperature, the faster the jet stream, which can reach speeds of up to 250 mph (402 kph) or greater, but average about 110 mph (177 kph).
Polar and Subtropical Jet Streams
Each hemisphere has two primary jet streams; a polar and a subtropical. The polar jet streams form between the latitudes of 50 and 60 degrees north and south of the equator, and the subtropical jet stream is closer to the equator and takes shape at latitudes of 20 to 30 degrees. While the polar and subtropical jet streams are the most known, other jet streams can form whenever wind speeds are above 58 mph in the upper atmosphere at about six miles to nine miles above the surface.
The question that everyone has been asking, how do jet streams affect the weather? Jet streams play a key role in the weather because they normally separate colder air and warmer air. Jet streams are responsible for pushing air masses around, which in return, moves weather systems to new areas. Jet streams usually do not follow a straight path. These patterns are called peaks and troughs, which shift and can result in poor forecasting predictions. When the jets streams are warmer, their ups and downs become more extreme, bringing different types of weather to areas that are not accustomed to climate variations. If the jet stream dips south, for example, it takes the colder air masses with it. Jet streams can have an impact on air travel and are used to determine flight patterns. Volcanoes have also played a role in understanding of the jet stream. Observers of the 1883 eruption of the Krakatoa volcanic island in Indonesia documented its effect on the sky, and in the 1920s Japanese meteorologist Wasaburo Oishi used aviator balloons to identify the jet stream from a site near Mt. Fuji. Many European flights were grounded after the 2009 eruption of Iceland’s Eyjafjallajokull volcano —further proof that plumes of volcanic ash have a tendency to get sucked into the same jet stream that airplanes use for travel.
In conclusion, jet streams can have a major impact on weather and weather patterns. Jet streams can be unpredictable and can bring many types of precipitation, with it. So, the next time you plan on traveling in a plane for vacation, you may just end up with a bumpy ride, depending on where the jet stream is moving through.