The phenomenon of 'atmospheric stagnation,' characterized by extreme weather such as summer heatwaves, winter cold snaps, and yellow dust due to climate change, is becoming more severe. American researchers have newly confirmed that humidity is a hidden factor that influences the intensity of this stagnation phenomenon. This discovery is expected to mark an important turning point in improving the accuracy of disaster weather forecasts.
On the 21st (local time), Professor Lei Wang and his research team from Purdue University confirmed that atmospheric stagnation is significantly affected by humidity. The jet stream in the upper atmosphere bends and appears to stop in certain areas, and depending on the air's humidity, the stagnation can either last longer or be released more easily.
Atmospheric stagnation is a phenomenon where the flow of air stops, causing weather patterns to become entangled, resulting in prolonged extreme weather. Until now, stagnation had been explained by dry air, but the Purdue University research team has newly identified the role of humidity.
Atmospheric stagnation is considered a serious problem in Korea as well. Previously, the National Institute of Meteorological Sciences analyzed that if climate change accelerates, the number of days with atmospheric stagnation in Korea could increase by 58% in 80 years.
Professor Wang said, "Since the early days of modern meteorology in the 1940s, most classical theories of atmospheric stagnation were based on the assumption of completely dry air. While useful for simplification, the actual atmosphere is not completely dry."
There are two forms of atmospheric stagnation: 'ridge' and 'dipole'. The ridge type occurs when high pressure intensifies, pushing the jet stream upward and causing heatwaves, while the dipole type has areas of high and low pressure adjacent to each other, fixing different weather in one place.
The research results showed that temperature changes due to humidity have different effects based on the form. In the ridge type, heat from humidity enhances the upstream wind flow, prolonging atmospheric stagnation, whereas in the dipole type, it weakens the central flow, confirming a reduction in intensity.
Professor Wang explained, "If we consider atmospheric stagnation as highway traffic congestion, humidity is like the condition of the road surface. When there is a lot of humidity, the road becomes slippery, making it easier for vehicles to get stuck; similarly, the flow of the atmosphere can become more congested."
The research team expects that this discovery will not only be an academic achievement but also a practical tool that forecasting agencies like the Korea Meteorological Administration can use. Once a new climate model including humidity is developed, the accuracy of long-term forecasts over a few weeks is expected to improve, greatly aiding preparations against disastrous heatwaves and cold snaps.
This research achievement was published last month in the international journal 'Nature Communications.'
References
Nature Communications (2025), DOI: https://doi.org/10.1038/s41467-025-60811-4