About Us
Founded in 1944, the American Committee for the Weizmann Institute of Science develops philanthropic support for the Weizmann Institute in Israel, and advances its mission of science for the benefit of humanity.
Sep 24, 1996...
REHOVOT, Israel—September 24, 1996—Prehistoric ashes can now be recognized and analyzed with precision for the first time, thanks to a discovery made by a Weizmann Institute of Science researcher.
The finding, reported in the September issue of the Journal of Archaeological Science, is expected to shed new light on the ways primitive humans used fire, and on their lifestyles and environment. While humans are believed to have first harnessed fire at least 500,000 years ago, ash—the most direct evidence of fire—is hard to find and even harder to recognize, because most of the minerals in it are highly reactive and unstable, and begin changing within days of a fire's going out.
https://www.weizmann-usa.org/news-media/in-the-news/recipe-unearthed-for-mystery-clouds/
Jul 18, 2017...
‘Mystery clouds’ of the type studied at the Weizmann Institute of Science, Israel. Photograph: Ilan Koren
The weather forecast had predicted a cloudless day, but when Ilan Koren, an atmospheric scientist, looked up he saw small “cotton wool” clouds dotted across the bright blue sky over Israel.“Mystery” clouds like these are common on hot sunny days along humid sub-tropical shores, like those along the Mediterranean. Yet classical physics suggests these clouds shouldn’t exist. Now scientists think they might have finally solved the puzzle of how mystery clouds are made.Convection is the usual process that creates clouds on a hot sunny day. Warm air rises above warm regions of land (such as macadamed car parks, ploughed fields and coniferous forests). As the parcel of air rises it cools and its ability to hold moisture decreases. Eventually, if it rises high enough, it cannot hold any more water so droplets form and a fluffy cloud appears.But the clouds that Koren saw were a puzzle because they occurred below the predicted 100% humidity level. To understand these mystery clouds, Koren, based at the Weizmann Institute of Science, with his colleagues observed clouds and made regular measurements of changes in temperature and humidity at different altitudes. This was done over a 92-day period in the summer of 2011.Using these measurements they simulated the likely atmospheric mixing, and discovered that the mystery clouds were caused by variations in humidity not at ground surface but a few hundred metres up, perhaps where moist ocean air was mixing with dry land air. Normally cumulus clouds are caused by temperature variations on the ground surface.Writing in the journal Environmental Research Letters the scientists estimated that these previously misunderstood clouds could be responsible for reflecting up to 4 watts per square metre – equivalent to the local warming effect from greenhouse gases.
Jan 07, 2015...
Brian Berkowitz is a professor at the Weizmann Institute of Science and head of its Department of Earth and Planetary Sciences. Photo courtesy of the Weizmann Institute
Ask Brian Berkowitz about the fruits of his research – say, an environmentally friendly way to remove pollutants from contaminated water – and he’ll stop you.
“OK. I have to go back a little bit,” he tells me. “I’m at the Weizmann Institute of Science, and the mandate is basic research, basic, curiosity-driven scientific research. So rather than try to solve a particular problem and directing research, we do the basics, understand basic phenomena and once you understand them, then we end up inevitably coming up with various solutions.”
Jul 07, 2017... In Israel’s earliest days, Weizmann Institute scientists invented a method for waxing oranges so they could be shipped, which was a major boon for the country’s then-fledgling, agriculture-based economy. Since those days, the Weizmann Institute of Science hasn’t stopped working toward improving food security — not just for Israel, but for the world. But today the task is more daunting than ever: by the mid-21st century there will be nine billion mouths to feed; and climate change is expected to have an impact on agriculture, possibly a considerably negative impact.
Apr 21, 2013...
A Lite-Trac four-wheeled self-propelled crop sprayer spraying pesticide on a field. photo credit: Lite-Trac/Wikipedia Commons
The Green Revolution may have saved a billion people from starvation, according to common wisdom, but the expansion of agricultural technology came at a price: A sharp increase in the use of pesticides and chemicals. These technologies have made it possible for farmers to grow the food needed for an ever-growing population, but they have wreaked havoc on the environment, with chemicals seeping into the groundwater and entering the food chain — setting off who-knows-what consequences in the long-term.
May 24, 2010...
Not all explosions are created equal: It’s as true for film effects as it is for the stars. Yet, until now, scientists had only observed two basic kinds of exploding stars, known as supernovae. Now, scientists at the Weizmann Institute of Science, in collaboration with others around the world, have identified a third type of supernova. Their findings appeared this week in Nature.
The first two types of supernova are either hot, young giants that go out in a violent display as they collapse under their own weight, or old, dense, white dwarves that blow up in a thermonuclear explosion. The new supernova appeared in telescope images in early January 2005, and scientists, seeing that it had recently begun the process of exploding, started collecting and combining data from different telescope sites around the world, measuring both the amount of material thrown off in the explosion and its chemical makeup. But Dr. Avishay Gal-Yam, Hagai Perets (now at the Harvard-Smithsonian Center for Astrophysics), Iair Arcavi, and Michael Kiewe of the Weizmann Institute’s Faculty of Physics, together with Paolo Mazzali of the Max-Planck Institute for Astrophysics, Germany, the Scuola Normale Superiore, Pisa, and INAF/Padova Observatory in Italy, Prof. David Arnett from the University of Arizona, and researchers from across the US, Canada, Chile, and the UK, soon found that the new supernova did not fit either of the known patterns.
https://www.weizmann-usa.org/news-media/news-releases/science-tips-july-2012/
Jul 27, 2012... As sulfur cycles through Earth’s atmosphere, oceans and land, it undergoes chemical changes that are often coupled to changes in other such elements as carbon and oxygen. Although this affects the concentration of free oxygen, sulfur has traditionally been portrayed as a secondary factor in regulating atmospheric oxygen, with most of the heavy lifting done by carbon. However, new findings that appeared this week in Science suggest that sulfur’s role may have been underestimated.
Mar 10, 2013...
The commercial arm of the Weizmann Institute of Science has signed an agreement with an agrochemicals firm to commercialize a new technology that impedes the permeation of toxic pesticides into groundwater, the companies have announced.
As enormous amounts of pesticides continue to be used around the world in an effort to increase the global demand for food, the durable toxic chemicals can often seep into the soil and remain there for years, thereby contaminating the groundwater, the firms explained. Aiming to reduce the risks of such environmental contamination, Prof. Brian Berkowitz and Dr. Ishai Dror developed a system at the Rehovot school’s department of environmental sciences and energy research that is designed to safely eradicate the toxins.
May 17, 2017... Water, Water Everywhere: Prof. Brian Berkowitz on Protecting a Precious Resource
Sep 01, 2019... Among the many ongoing changes inflicted on our climate and atmosphere, the increase in CO2 level has been the most consistent, with about 1.5-2 ppm annual increase. CO2 is the substrate for plant photosynthesis, and hence the expectation that the more CO2 we emit to the air, the more CO2 is available for plant growth. Indeed, CO2 fertilization has been used successfully to increase yields in greenhouses. Yet, in the majority of scenarios outside the greenhouse, plant growth is limited by other factors, such as light, water, and nutrients. Therefore, so far, global crop yields have not benefitted from surplus CO2.
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