Streams are a fast flowing, narrow river of high winds that encircling the globe for hundreds of miles, it flows several miles high above the ground. Earth typically has two or three jet streams in each hemisphere. When two air masses that have different densities meet and where they conduct the strongest winds is where a jet stream is formed. There are two major jet streams in each hemisphere the polar jet stream and the subtropical jet stream.
The subtropical jet stream stays at about 20 to 30 degrees latitude while the polar jet stream position varies between 50 and 60 degrees latitude . Jet streams are found in the tropopause layer of the atmosphere, this layer extends from the surface of the earth to 6.2 miles in the air, and most weather occurs in this layer . This research paper is going to take a closer look at the polar jet stream, and the impact it has on the weather. Based on the preponderance of evidence found jet streams are becoming weaker, leading to warmer temperatures and extreme weather in the Northern Hemisphere.
An article published by the New York Times shows a graph about winter temperatures between the years 1989 and 2018, and the months from December to February . In the graph, the data is compared to a baseline of the average 20th century temperature. The date for this graph comes from the National Oceanic and Atmospheric Administration. Based on the data in the graph you can conclude that winter temperatures have indeed been rising.
Within the past 30 years, from 1988 to 2018, twenty-three of the winters have higher temperatures than the average in the 20th century. Eleven of those years the temperature has been more than three degrees above the average, while in the earlier 90 years it only reached that high four times. The New York Times stated that jet streams were a cause the rising temperatures.
Jet streams help to shape the weather in each hemisphere by moving further north or south and pulling with them colder air from the Arctic or warmer air from the equator. They get their power from the high or low air pressure . Over the top of the earth’s North and South Poles is a large area of low air pressure called the polar vortex.
The jet stream becomes wavier when the vortex weakens, allowing the cold air to push south in some areas while warm air pushes up in other areas. A strong jet stream has a large amount of pressure applied to it from the cold air of the Arctic, allowing for the jet stream to have a straighter path.
Jet streams are changing, one reason for these changes is climate change. Jet streams are becoming weaker, causing them to wobble more with a greater risk of getting stuck and causing longer periods of extreme weather. With jet streams controlling the weather patterns, they can cause extreme weather to happen, such as flooding, droughts, heat waves, and cold snaps.
With the melting ice in the Arctic the air is warming up there is less low air pressure pushing against the polar vortex. An Insideclimate News report claims that the scientist involved in Arctic ice melting research think that there’s clear evidence pointing towards temperatures rising faster in the Arctic than the rest of the planet . With warming temperatures, it’s reducing the amount of ice in the Arctic, which is leading to a weaker polar vortex.
A polar vortex is a large area that surrounds the north and south poles of the earth . The large area is made up of cold air and low air pressure. During the winter the polar vortex is strong and its weak during the summer. With the ice melting in the Arctic there is less cold air and air pressure being produced, with leads to weak a polar vortex. A weak polar vortex leads to a weak jet stream because less air pressure is pushing the jet stream further south. The weakening of the polar vortex is allowing more cold air to escape and move further south, causing the jet stream to wobble .
The polar vortex has never stayed at a consistent strength, it’s always varying. It’s been found that the jet stream is staying weaker for longer periods of time due to a weakening polar vortex. There are many pieces of evidence in published articles to help support the claim that jet streams are getting stuck and temperatures are rising in the Arctic. An article published by New Scientist discusses an extended heat wave that happened in the northern hemisphere in 2018 .
This article states that the heat wave was the result of a weak jet stream that got stuck, that’s majorly caused by the warming temperatures in the Arctic. In 2018 heatwaves where the cause of dozens of deaths across Asia, dry weather in Europe, and wildfires in Sweden and California. In another article published by Journal of Climate, it states that the warmest winter on record for the Arctic was 2015-2016 .
Some causes of the recent warmer winters of the Arctic could include sea ice loss, the release of greenhouse gasses increases, and energy transfer in the atmosphere and the ocean . With the unusually warm temperatures in the Arctic, it may have a huge influence on the weather and extreme weather all around the globe.
By looking at the evidence in this paper you can find that warmer temperatures and extreme weather are occurring in the Northern Hemisphere caused by the polar jet streams becoming weaker. One factor that could be leading to a weaker polar jet stream is the melting ice in the Arctic. The most powerful jet streams are created when there is a great difference in temperature between the high and low air pressures.
The temperature in the Arctic is warming and the gap in temperature between the high and low air pressures is shrinking, causing a weak jet stream. By taking a look at different articles you can see evidence that the jet stream is, in fact getting stuck and is becoming weaker, causing a change in weather and extreme weather to occur more often. Further research is needed to fully investigate what other changes have occurred on earth to cause a change in the polar jet stream?