The Chinese and Israeli researchers showed that the average precipitation on Mount Hua near Xian in central China has decreased by 20 percent along with increasing levels of manmade air pollution during the last 50 years. The precipitation loss was doubled on days that had the poorest visibility due to pollution particles in the air.
This explains the widely observed trends of decrease in mountain precipitation relative to the rainfall in nearby densely populated lowlands, which until now had not been directly ascribed to air pollution.
The research study, published in the current issue of the journal Science, is titled “Inverse Relations between Amounts of Air Pollution and Orographic Precipitation” and was written by Prof. Rosenfeld of the Hebrew University’s Ring Department of Atmospheric Sciences, Jin Dai and others from the Meteorological Institute of Shaanxi Province, China, and Zhanyu Yao of the Chinese Academy of Meteorological Science.
These findings highlight the threat to vital water resources in polluted regions of the world where hilly-area precipitation makes a significant contribution to the regional water supply, as in the southwestern U.S. central and northern China, and the Middle East. The importance of that is underlined by the realization that it is not high temperatures due to global warming but rather the lack of water that makes a region into an unlivable desert.
The authors studied observations of precipitation and visibility starting in 1954 at the top of Mount Hua. They linked the decreasing visibility at its over two-kilometer-high summit with increasing air pollution particles that reach to the clouds. They were able to show that the trend of higher concentrations of these fine, airborne, pollutants (aerosols) is responsible for the observed decreasing trend of mountain precipitation. This is the first time that this link has been demonstrated so conclusively.
The precipitation inhibition process occurs as water vapor condenses on the pollution particles and creates a cloud with a large number of drops that are so small that they float with the air and are slow to coalesce into raindrops or to freeze into sleet and snowflakes. This slowing translates into a net loss of precipitation when the cloud “lifetime” is shorter than the time necessary to release its water. This is the case for clouds that form when they ascend across a ridge and then descend and evaporate on the downwind side.
By making use of precipitation and visibility records that show a direct causal link between the airborne particle pollution and the mountain precipitation losses, the unique China study can serve as a template to bear out hypotheses about the effects of pollution on rainfall that were undertaken previously by Prof. Rosenfeld in hilly regions with similar pollutive conditions. These include California and much of the western United States. Similar trends were already published also for Israel, and observed in South Africa, Portugal, France, Switzerland, Morocco, Canada, Greece and Spain.
Atmospheric aerosols have been described in earlier studies as playing a role in cooling the atmosphere by reflecting some of the incoming solar radiation back into space -- thus serving as a counterbalance to global warming resulting from the release of greenhouse gases. The latest study by Prof. Rosenfeld and his Chinese associates shows, however, that this “beneficial” effect is offset by the proven direct link between air pollution and decreased mountain precipitation, and that climate change means much more than “just” global warming.
Jerry Barach | alfa
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
22.03.2018 | Trade Fair News
22.03.2018 | Earth Sciences
22.03.2018 | Earth Sciences