Snowbound: Big trees boost water in forests by protecting snowpack

Read the full story from Utah State University.

Trees have a complex relationship with snow and energy as the season warms up, but new research shows that big trees can protect melting snowpacks in water-stressed environments.

Can cloud seeding help quench the thirst of the U.S. West?

Read the full story at e360.

In the midst of an historic megadrought, states in the American West are embracing cloud seeding to increase snow and rainfall. Recent research suggests that the decades-old approach can be effective, though questions remain about how much water it can wring from the sky.

Global science project links Android phones with satellites to improve weather forecasts

Read the full story from The Verge.

Collecting satellite data for research is a group effort thanks to this app developed for Android users. Camaliot is a campaign funded by the European Space Agency, and its first project focuses on making smartphone owners around the world part of a project that can help improve weather forecasts by using your phone’s GPS receiver.

The Camaliot app works on devices running Android version 7.0 or later that support satellite navigation. The way satellite navigation works, phones or other receivers look for signals from a network of satellites that maintain a fixed orbit. The satellites send messages with the time and their location, and once it’s received, the phones note how long each message took to arrive, then use that data to figure out where on Earth they are.

Researchers think that they can use satellite signals to get more information about the atmosphere. For example, the amount of water vapor in the atmosphere can affect how a satellite signal travels through the air to something like a phone.

Climate scientists reconsider the meaning and implications of drought in light of a changing world

Read the full story at the University of California Santa Barbara.

Maps of the American West have featured ever darker shades of red over the past two decades. The colors illustrate the unprecedented drought blighting the region. In some areas, conditions have blown past severe and extreme drought into exceptional drought. But rather than add more superlatives to our descriptions, one group of scientists believes it’s time to reconsider the very definition of drought.

Cloud seeding might not be as promising as drought-troubled states hope

Cloud seeding equipment near Winter Park in Colorado. Denver Water

by William R. Cotton, Colorado State University

Forecasters at the National Oceanic and Atmospheric Administration issued their U.S. spring outlook on March 17, 2022, and their top concern was worsening drought in the West and southern Plains. Several western states have experimented with cloud seeding to try to increase precipitation, but how well does that actually work? Atmospheric scientist William Cotton explains.

On mountain peaks scattered across Colorado, machines are set up to fire chemicals into the clouds in attempts to generate snow. The process is called cloud seeding, and as global temperatures rise, more countries and drought-troubled states are using it in sometimes desperate efforts to modify the weather.

But cloud seeding isn’t as simple as it sounds, and it might not be as promising as people wish.

As an atmospheric scientist, I have studied and written about weather modification for 50 years. Cloud seeding experiments that produce snow or rain require the right kind of clouds with enough moisture, and the right temperature and wind conditions. The percentage increases in precipitation are small, and it’s difficult to tell when snow or rain fell naturally and when it was triggered by seeding.

How modern cloud seeding began

The modern age of weather modification began in the 1940s in Schenectady, New York.

Vince Schaefer, a scientist working for General Electric, discovered that adding small pellets of dry ice to a freezer containing “supercooled” water droplets triggered a proliferation of ice crystals.

Other scientists had theorized that the right mix of supercooled water drops and ice crystals could cause precipitation. Snow forms when ice crystals in clouds stick together. If ice-forming particles could be added to clouds, the scientists reasoned, moisture that would otherwise evaporate might have a greater chance of falling. Schaefer proved it could work.

On Nov. 13, 1946, Schaefer dropped crushed dry ice from a plane into supercooled stratus clouds. “I looked toward the rear and was thrilled to see long streamers of snow falling from the base of the cloud through which we had just passed,” he wrote in his journal. A few days later, he wrote that trying the same technique appeared to have improved visibility in fog.

A man looks into a freezer looking amazed at what he sees.
Vincent Schaefer, in foreground, examines snow created in a modified GE freezer in 1947, with Irving Langmuir, at left, and Bernard Vonnegut. General Electric Company/Museum of Science and Innovation

A colleague at GE, Bernie Vonnegut, searched through chemical tables for materials with a crystallographic structure similar to ice and discovered that a smoke of silver iodide particles could have the same effect at temperatures below -20 C (-4 F) as dry ice.

Their research led to Project Cirrus, a joint civilian-military program that explored seeding a variety of clouds, including supercooled stratus clouds, cumulus clouds and even hurricanes. Within a few years, communities and companies that rely on water were spending US$3 million to $5 million a year on cloud-seeding projects, particularly in the drought-troubled western U.S., according to congressional testimony in the early 1950s.

But does cloud seeding actually work?

The results of about 70 years of research into the effectiveness of cloud seeding are mixed.

Most scientific studies aimed at evaluating the effects of seeding cumulus clouds have shown little to no effect. However, the results of seeding wintertime orographic clouds – clouds that form as air rises over a mountain – have shown increases in precipitation.

There are two basic approaches to cloud seeding. One is to seed supercooled clouds with silver iodide or dry ice, causing ice crystals to grow, consume moisture from the cloud and fall as snow or rain. It might be shot into the clouds in rockets or sprayed from an airplane or mountaintop. The second involves warm clouds and hygroscopic materials like salt particles. These particles take on water vapor, becoming larger to fall faster.

A drawing of a plane flying
An illustration of cloud-seeding processes. Naomi E. Tesla/Wikipedia, CC BY

The amount of snow or rain tied to cloud seeding has varied, with up to 14% reported in experiments in Australia. In the U.S., studies have found a few percentage points of increase in precipitation. In a 2020 study, scientists used radar to watch as 20 minutes of cloud seeding caused moisture inside clouds to thicken and fall. In all, about one-tenth of a millimeter of snow accumulated on the ground below in a little over an hour.

Another study, in 2015, used climate data and a six-year cloud-seeding experiment in the mountains of Wyoming to estimate that conditions there were right for cloud seeding about a quarter of the time from November to April. But the results likely would increase the snowpack by no more than about 1.5% for the season.

While encouraging, these experiments have by no means reached the level of significance that Schaefer and his colleagues had anticipated.

Weather modification is gaining interest again

Scientists today are continuing to carry out randomized seeding experiments to determine when cloud seeding enhances precipitation and by how much.

People have raised a few concerns about negative effects from cloud seeding, but those effects appear to be minor. Silver ion is a toxic heavy metal, but the amount of silver iodide in seeded snowpack is so small that extremely sensitive instrumentation must be used to detect its presence.

A man attaches a row of canisters to an airplane wing.
Several companies attempt cloud seeding from airplanes. AP Photo/Dave Kolpack

Meanwhile, extreme weather and droughts are increasing interest in weather modification.

The World Meteorological Organization reported in 2017 that weather modification programs, including suppressing crop-damaging hail and increasing rain and snowfall, were underway in more than 50 countries. My home state of Colorado has supported cloud-seeding operations for years. Regardless of the mixed evidence, many communities are counting on it to work.

This article was updated March 17, 2022, with NOAA’s U.S. spring climate and weather outlook.

William R. Cotton, Professor Emeritus of Meteorology, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

California Department of Water Resources launches new website to improve tracking of local and statewide water conditions

View of snow covered Sierra Nevada mountains in Nevada County, California
View of snow covered Sierra Nevada mountains in Nevada County, California

Source: California Department of Water Resources

The Department of Water Resources (DWR) has launched a new website, California Water Watch, that helps Californians easily access information on current local and statewide water conditions – down to their own region and even neighborhood.

“The variability of California’s climate and current water conditions we are experiencing now make this data more important than ever. Climate whiplash is our new reality living in this State, and we are innovating and developing new tools like California Water Watch to provide water managers, researchers, and policymakers with the data necessary to make better informed decisions about our limited water supply,” said DWR Director Karla Nemeth.

The website brings together data from DWR and other sources to provide dynamic real-time information on precipitation, temperature, reservoirs, snowpack, groundwater, streamflow, soil moisture, and vegetation conditions. Users can enter an address to see local conditions, including daily precipitation and temperature statistics, for their area and links to water supplier information. The website also allows users to compare data on local conditions by year and by region.

The website was developed in response to Governor Newsom’s call for a California-centric version of the U.S. Drought Monitor website in his drought state of emergency proclamation. The website was also recommended in the California Natural Resources Agency’s report to the Legislature on lessons learned from the 2012-2016 drought.

California Water Watch also includes precipitation forecast maps and links to other forecasting products, all from one easy-to-use web page. Regular hydroclimate summaries developed by California State Climatologist Mike Anderson will also be posted to the California Water Watch website. These summaries will succinctly describe what current water conditions look like in California and their impacts on the current drought.

California Water Watch is just one of many tools being leveraged and developed by DWR to keep Californians informed about current conditions and to improve water supply forecasting. For more information or to access the California Water Watch website today, visit For information about other DWR and State drought response efforts and funding programs, visit

For more information: Akiela Moses, Information Officer, Public Affairs, Department of Water Resources, 916-820-7669 |

National Science Foundation funds project to improve weather forecasts for cities

by Lisa Sheppard, Prairie Research Institute

Scientists at the Illinois State Water Survey (ISWS) have begun a new project that will ultimately improve weather forecasting of severe storms and heatwaves in cities across the US.

In the three-year project with a budget of over $850,000 from the National Science Foundation (NSF), ISWS will focus on improving weather forecasts for the Chicago, New York, and Denver metro areas using observations from space and from the ground combined with numerical model development. The goal is to study the chemistry, atmosphere, and human adaptive choices that influence storms and heatwaves over cities.

“We’ve long realized there is a gap in the fundamental knowledge of urban weather and climate processes, as well as our inability to accurately capture the magnitude, intensity, and locations where severe storms and heatwaves occur,” said research climatologist and principal investigator Ashish Sharma. “Weather forecasts can see where storms will occur, but we need to use improved models to understand storms in a better way.”

These gaps can be addressed by developing integrated weather and chemistry models for urban areas through new model development activities and using a suite of observations from the ground and satellites.

“We are thrilled that NSF has supported ISWS to lead cutting-edge fundamental and applied research in urban climate modeling,” said Kevin OBrien, director of ISWS. “This is a great example of how ISWS is taking a deeper dive into how we can make cities more resilient to climate change impacts.”

For this study, the Integrated Urban Climate Research group, led by Sharma, will analyze the contribution of urban surface heat emissions and pollutants to storms and heatwaves, examine the effects of the interaction between the atmosphere and complex urban land surface characteristics, and study the impacts of future urban development and green infrastructure interventions. Strengthening our capabilities and advancing our knowledge in integrated urban modeling will likely improve weather forecasting capabilities for cities.

“This will be the first model development effort to include chemistry-weather interactions in urban climate models. The more realistic that models are, the more accurate they are in simulating extreme weather,” said Sharma.

The project will help city managers and stakeholders to assess environmental risks and vulnerabilities and identify where and which infrastructure choices, such as green, cool, or photovoltaic roofs, are best suited to reduce environmental, social, and health inequities in cities.  

“Outputs from the project will help urban planners and practitioners make decisions that can protect vulnerable communities and restore environmental justice in the Chicago metro area,” said Edith Makra, director of environmental initiatives and the project collaborator at the Metropolitan Mayors Caucus. “Urban solutions require money and manpower, so it takes a coordinated effort from scientists and community representatives from different disciplines to solve these types of problems.”

The project team will coordinate with the Chicago National Weather Service to determine how the model enhancements and new developments can help improve weather forecasting and climate change projections for urban communities. At the end of the study, the team will be able to recommend resilient environmental mitigation solutions to the three metro areas. They will also continue to partner with municipalities, agencies, and institutions in the Chicago, Denver, and New York metro areas to share study findings.

The project includes co-principal investigators at the University of Illinois and University of Notre Dame and collaborators at the National Center for Atmospheric Research in Boulder and NASA.

Media contact: Ashish Sharma, 217-300-8423,

This story originally appeared on the Prairie Research Institute News Blog. Read the original story.

Celebrate Women’s History Month with six inspiring women in atmospheric sciences

Read the full story in the Washington Post.

This International Women’s Day, we are inspired by these six scientists making a difference in Earth sciences and meteorology.

Citing drought, US won’t give water to California farmers

Read the full story from the Associated Press.

With California entering the third year of severe drought, federal officials said Wednesday they won’t deliver any water to farmers in the state’s major agricultural region — a decision that will force many to plant fewer crops in the fertile soil that yields the bulk of the nation’s fruits, nuts and vegetables.

Co-occurring droughts could threaten global food security

Read the full story from Washington State University.

Droughts occurring at the same time across different regions of the planet could place an unprecedented strain on the global agricultural system and threaten the water security of millions of people, according to a new study in Nature Climate Change