The summer of 2024 was officially the summer of the Northern Hemisphere hottest ever recordedIn the United States, there appeared to be severe heat waves somewhere almost every single day.
Phoenix reached 100 degrees for greater than 100 days The 2024 Olympic Games began amid a chronic heatwave in Europe that has affected the three hottest days since weather records began worldwide21-23 July. August was The hottest month on earth within the 175-year records of the National Oceanic and Atmospheric Administration.
Overall, the worldwide average temperature was 2.74 degrees Fahrenheit (1.52 degrees Celsius) above the common of the twentieth century.
This could seem small, however the temperature increases related to human-caused climate change don’t occur as small, uniform increases across the planet. Rather, they result in more often and severe heat waves like those the world experienced in 2024.
The most severe and chronic heat waves are sometimes related to an atmospheric pattern called a heat dome. an atmospheric scientistI study weather patterns and climate change. Here you’ll find out how heat domes, the jet stream and climate change affect summer heat waves and the record summer of 2024.
What the jet stream has to do with heat domes
If you’ve got listened Weather forecasts throughout the Summer 2024you’ve got probably heard the term “heat dome” over and over.
A heat dome is a everlasting High pressure system over a big area. A high pressure area is formed by sinking air. As the air sinks, it heats up, lowering relative humidity and creating sunny weather. The high pressure also acts as a lid that stops hot air from rising and dispersing on the surface. The resulting heat dome can last for days and even weeks.
The longer a heat dome exists, the more heat builds up and the more sweltering the conditions are for people on the bottom.
NOAA
How long these heat domes last depends largely on the jet stream.
The jet stream is a narrow band of strong winds within the upper atmosphere, about 30,000 feet above sea level. Due to the rotation of the earth, it moves from west to east. The strong winds are a results of the strong temperature differences where in the center latitudes the nice and cozy tropical air meets the cold polar air from the north.
The jet stream doesn’t follow a straight path. Rather, it meanders north and south in a wave-like pattern. These huge meanders are generally known as Rossby wavesthey usually have an enormous influence on the weather.
NASA/Goddard Space Flight Center Scientific Visualization Studio
Where the jet stream turns north, form a ridgea high pressure area forms south of the wave. Where the jet stream descends to the south and forms a trough, a low pressure area forms north of the jet stream. A low pressure area incorporates rising air in the middle, which cools and tends to supply precipitation and storms.
Our weather is basically influenced by the position and characteristics of the jet stream.
How climate change affects the jet stream
The jet stream or every other wind is the results of differences in surface temperature.
Put simply, warm air rises and creates low pressure, and cold air sinks and creates high pressure. Wind is the Movement of air from high to low pressure. Larger temperature differences result in stronger winds.
On the Earth as a complete, warm air rises near the equator, while cold air sinks near the poles. The temperature difference between the equator and the poles determines the strength of the jet stream in each hemisphere.
However, this temperature difference has modified, especially within the Northern Hemisphere. The Arctic region is warming by thrice faster than the worldwide average. This phenomenon, generally known as Arctic amplification, is basically attributable to the Melting of Arctic sea iceallowing the exposed dark water to soak up more solar radiation and warm up faster.
As the Arctic warms faster than the tropics, the temperature difference between the 2 regions decreases. And that slows down the jet stream.
As the jet stream slows down, it tends to meander more, leading to larger waves. The larger waves create larger high pressure areas. These can often be blocked by the deep low pressure areas on each side, in order that the high pressure area stays over a big area for a protracted time frame.
Normally, the jet stream waves move through the continental United States in about three to 5 days. However, if a blockage occurs, could stagnate for days or perhaps weeksThis could cause heat to accumulate underneath and result in extreme heat waves.
As the jet stream circles the globe, stagnant waves could occur in several places, resulting in simultaneous heat waves in mid-latitudes world wide. This happened in 2024, with long-lasting heat waves in Europe, North America, Central Asia and China.
The behavior of the jet stream also influences winter
The same meandering behavior of the jet stream also plays a job in extreme winter weather, including the southward intrusion of frigid polar air from the polar vortex and conditions for severe winter storms.
Many of those atmospheric changes attributable to human-induced global warming have significant impacts on people's health, property, and ecosystems world wide.
image credit : theconversation.com