This is one in a series on careers in science, technology, engineering and mathematics made possible with generous support from Arconic Foundation.
Along a sun-drenched coastline, puffy little clouds stretch to the horizon like a vast set of beach umbrellas. Strolling along the sand or splashing in the surf, you probably wouldn’t even notice them.
Paquita Zuidema does, though. She is an atmospheric scientist at the University of Miami in Florida. And she notes that most people don’t appreciate these marine low clouds. “They aren’t very interesting from a weather point of view,” she admits. They’re small. They don’t cause big storms. They barely even produce rain. Yet marine low clouds intrigue her far more than other, flashier ones.
In part because there are so many of them, these clouds are very effective at reflecting sunlight, she explains. Layers of the bright white clouds can stretch for miles. By keeping some of the sun’s energy from reaching Earth’s surface, those clouds help keep Earth relatively cool.
When most of us see clouds, we see animal shapes, a chance of rain or maybe a bit of welcome shade. Scientists, such as Zuidema, see much, much more. For these researchers, clouds are an integral part of the planet, transferring water, dust and even life around the globe.
Little clouds that can
As a kid, Zuidema wanted to be a naturalist — a scientist who looks at the natural world in a broad way. She now thinks that was “kind of a romantic vision.” When she got to college, she picked what she thought was a more practical path, studying physics along with public policy. That combination led her to atmospheric sciences.
But Zuidema didn’t really notice low clouds until graduate school at the University of Washington, in Seattle. That city “has a lot of low clouds,” the scientist says. She suddenly realized how important their reflection of heat back into space was for Earth’s climate. She continued studying low clouds at the University of Colorado in Boulder. There she earned her PhD.
Seattle’s skies may be home to plenty of low clouds, but there are even better places to spot these little puffs. The greatest gatherings tend to occur off the coasts of places like Namibia, in Africa, and northern Chile. These places are home to some of Earth’s driest deserts. At about 430 to 600 meters (some 1,400 to 2,000 feet) above the surface, moist air rising from the ocean cools and condenses into clouds. But instead of growing taller, the clouds are trapped by the dry, sinking air that creates desert conditions. The result is a layer, or deck, of marine low clouds. They can stretch for miles.
“The marine clouds are trying to rise but are being squished down,” Zuidema explains. Though most of these clouds form over oceans, they can be found anywhere warm moist air is pressed down by dry, descending air.
The more Zuidema learns about these little clouds, the more fascinating she finds them. “I’m really interested in the myriad ways these low clouds respond to their environment,” she says. Because there are so many low clouds, and because they help keep Earth cool by reflecting heat, anything that affects them can also affect overall climate. “It feeds back to the whole energy balance of the planet," she explains.
Lately Zuidema has been exploring how smoke that drifts over decks of marine clouds might change the way that these clouds absorb or reflect sunlight. Such smoke — from burning trees and grasses — can drift thousands of kilometers. If that smoke affects clouds, it might also affect climate. Last year, she spent a month on remote Ascension Island in the South Atlantic Ocean setting up instruments to track the interaction between low clouds there and smoke from southern Africa.
Zuidema appreciates the variety in her work. Besides the occasional trip to distant islands, she also teaches and collaborates with other scientists to better understand Earth’s climate system. Along the way, she’s helping elevate one type of low cloud into the spotlight it deserves.
Catch and release clouds
The ancient West African town of Sidi Ifni sits on the coast of Morocco. Here, on the edge of the bone-dry Sahara Desert, there’s never seems to be enough water to go around. For many women and girls here, carrying water from distant wells has become a day-long chore. As drought has worsened, many villagers have simply left. Today, communities and traditions there are crumbling.
Yet, half the year, water surrounds Sidi Ifni. There’s just one big problem: It’s locked into dense fog — clouds that touch the ground. Sidi Ifni isn’t alone. Thirsty coastal dwellers in Peru, Chile and Namibia also suffer thirst, even as they also are often cloaked in moist fog.
But imagine catching that water, the way spider webs get drippy in the mist.
In fact, people have figured out how to do just that. Some have set up tall nets high above dusty-dry villages at sites spanning from Morocco to Peru. Fog condenses onto the nets, then runs into tanks. At Sidi Ifni, fog nets now reel in about 6,300 liters (1,700 gallons) of water per day. That’s enough for 400 people. It also means that this town has a future again.
Still, fog catching is far from perfect. The nets need wind to push the fog into them. So the nets must be vertical. And that means they can get blown over. Plus, they work only when the fog is very dense.
Thousands of miles from Morocco, Catarina Esteves is working on improving this method of mining water from fog. Esteves is a materials scientist at Eindhoven University of Technology in the Netherlands. She has invented a high-tech fabric that she hopes will help wring even more water from the sky.
Esteves grew up on the coast of Portugal. There, she had plenty of access to water. Indeed, she used to regularly hang out at the beach. In college, she started out studying chemistry. With time, though, she changed her focus to materials science, which combines engineering with chemistry. After earning her PhD, she joined the faculty at Eindhoven.
This researcher likes that she can apply materials engineering to solve real-world problems. She is especially interested in nanomaterials: extremely small substances.
“One of my fields of interest is called ‘smart coatings,’” she says. She creates these with nanomaterials. Coatings, such as paint, are everywhere, she explains. But her nano-based coatings go much further. “We call it ‘smart’ because it responds to different needs.”
For instance, one of her students, a few years ago, wanted to create a nano-coated smart fabric. The goal was that it should switch from attracting water to repelling it. Imagine how sweat-soaked athletic clothes would dry instantly.
So her team experimented, coating cotton with nanomaterials.
Eventually, the team produced a fabric with remarkable moisture-capturing properties. “We found it had an extreme ability to draw water, even from air,” says Esteves. Better yet, the nano-coated cotton will release the water automatically. “From 18 to 30 degrees Celsius [64 to 86 degrees Fahrenheit], it soaks up water,” she notes. Once the temperature gets a bit warmer than that, the fabric switches and “releases all the water.”
When Esteves heard about the idea of fog-catching, “Suddenly, a light bulb went off.” The scientist thought: “What if we were able to use this fabric to draw water from fog?” The novel fabric’s unusual properties meshed perfectly with fog mining. This fabric could sponge up water when the air is cool and misty, then release it as that fog gives way to hot, sunny skies.
Right now, her team’s smart fabric is still in the experimental phase. That means it’s not quite ready for real-world projects, Esteves says. But someday, she hopes, it will be the super-soaker of fog catching. “It could really make people’s lives better,” she says.
Dale Griffin’s favorite clouds aren’t white and puffy, like Zuidema’s. They aren’t even made of water vapor, as is Esteves’ fog. Instead, his go-to clouds are thick airborne plumes of African dust.
Griffin didn’t always study clouds. With a master’s degree in public health and a PhD in microbiology — the study of germs — he began his career tracking waterborne bacteria that can make people sick. His job included flushing a colored chemical down people’s toilets to determine where the now-colored water went.
Then Griffin learned about another place microbes might be hiding: high in the sky. Intense winds regularly scour dust from the deserts of North Africa. Each year, at least 1.5 billion tons of this red dust sail from one side of the Atlantic Ocean to the other. Those clouds of dust helped build Caribbean Islands, such as the Bahamas and the Virgin Islands. They nourish the lush forests of the Amazon. Some of that dust even migrates to the United States. If you bite into a tomato from Florida, chances are it was grown in soil that started as African dust.
Yet until about 15 years ago, scientists figured that any bacteria or fungus picked up along with the dust would die on its journey across the ocean. “Most people thought that ultraviolet exposure [from the sun] would kill anything,” Griffin explains.
Then one day Griffin saw a satellite image of a massive dust cloud blowing off of North Africa. He began to question whether those scientists had been right. “That cloud of dust was the size of Spain,” he says. “I thought, we should be able to find something in that.” That moment, he now recalls, was “game-changing.”
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Intrigued, Griffin joined the U.S. Geological Survey (USGS) in St. Petersburg, Fla. This agency had been looking for someone to study airborne germs. There’s even a name for what is now his field of research: aeromicrobiology.
To determine what might be living in those gritty clouds, Griffin and his colleagues collect air samples from Caribbean hilltops on days when African dust turns the sky orange. They place the samples in petri dishes. Then they wait and watch to see what grows. A petri dish is a shallow dish used to nurture bacteria and other microbes. In one of them, a single cell may proliferate into a whole colony. And having a colony makes it easier for scientists such as Griffin to identify and study the cellular residents under a microscope.
Griffin has found that most sky-high microbes do die as they sail across the Atlantic skies. Still, there also are plenty of survivors.
“When you are talking about this much quantity, it doesn’t matter if you kill off 95 percent,” he says. The ones that survive tend to have been those that travelled near the bottom of the dust clouds. There they would have been screened from much of the sun’s harmful rays.
Cells with natural pigments, rather than being transparent, also have a better chance of making it. That pigment acts like a sunscreen, protecting those high-flying cells from killer rays.
The journey takes three to five days. So far, about one-fifth of the living survivors that Griffin and others have identified blowing in the wind can cause disease. One type infects ocean corals. Another can sicken sycamore trees. Scientists have even discovered pesticides, tiny amounts of metals and live grasshoppers riding the skies on African dust clouds.
Griffin likes his work and appreciates the freedom he has with the USGS. “They encourage innovation and different ideas that help us understand how the whole planet functions,” he says. That freedom gives him the chance to imagine and explore the unexpected connection between microbes, disease and long-distance dust.
After all, most people just think of rain when they look at a cloud. Griffin’s view is different. “I look at a cloud,” he says, “and I think ‘life!’”
Atlantic One of the world’s five oceans, it is second in size only to the Pacific. It separates Europe and Africa to the east from North and South America to the west.
cell The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
chemistry The field of science that deals with the composition, structure and properties of substances and how they interact. Chemists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances.
climate The weather conditions that typically exist in one area, in general, or over a long period.
cloud A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents. (in atmospheric science) A mass of airborne water droplets and ice crystals that travel as a plume, usually high in Earth’s atmosphere. Its movement is driven by winds.
colleague Someone who works with another; a co-worker or team member.
condense To become thicker and more dense. This could occur, for instance, when moisture evaporates out of a liquid. Condense can also mean to change from a gas or a vapor into a liquid. This could occur, for instance, when water molecules in the air join together to become droplets of water.
coral Marine animals that often produce a hard and stony exoskeleton and tend to live on reefs (the exoskeletons of dead ancestor corals.
drought An extended period of abnormally low rainfall; a shortage of water resulting from this.
engineering The field of research that uses math and science to solve practical problems.
environment The sum of all of the things that exist around some organism or some device and the condition those things create for that organism or device. Environment may refer to the weather and ecosystem in which some animal lives.
fabric Any flexible material that is woven, knitted or can be fused into a sheet by heat.
field An area of study, as in: Her field of research was biology.
fog A thick cloud of water droplets that touches the ground.
geological Adjective to describe things related to Earth’s physical structure and substance, its history and the processes that act on it. People who work in this field are known as geologists.
graduate school A university program that offers advanced degrees, such as a Master’s or PhD degree. It’s called graduate school because it is started only after someone has already graduated from college (usually with a four-year degree).
infect To spread a disease from one organism to another. This usually involves introducing some sort of disease-causing germ to an individual.
innovation (v. to innovate; adj. innovative) An adaptation or improvement to an existing idea, process or product that is new, clever, more effective or more practical.
marine Having to do with the ocean world or environment.
Master’s degree A university graduate degree for advanced study, usually requiring a year or two of work, for people who have already graduated from college.
materials engineering The design of new substances, focusing on how their atomic and molecular structure affects their overall properties. Materials engineers can create new materials or gain important insights by probing existing materials. Their analyses of a material’s overall properties (such as density, strength and melting point) can lead to the creation of novel materials that are tailor-made for some new use.
materials science The study of how the atomic and molecular structure of a material is related to its overall properties.
microbe Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.
microbiology The study of microorganisms, principally bacteria, fungi and viruses. Scientists who study microbes and the infections they can cause or ways that they can interact with their environment are known as microbiologists.
nano A prefix indicating a billionth. In the metric system of measurements, it’s often used as an abbreviation to refer to objects that are a billionth of a meter long or in diameter.
naturalist A biologist who works in the field (such as in forests, swamps or tundra) and studies the interconnections between wildlife that make up local ecosystems.
organism Any living thing.
pesticide A chemical or mix of compounds used to kill insects, rodents or other organisms harmful to cultivated plants, pets or livestock; or unwanted organisms that infest homes, offices, farm buildings and other protected structures.
petri dish A shallow, circular dish used to grow bacteria or other microorganisms.
PhD (also known as a doctorate) A type of advanced degree offered by universities — typically after five or six years of study — for work that creates new knowledge. People qualify to begin this type of graduate study only after having first completed a college degree (a program that typically takes four years of study).
physics The scientific study of the nature and properties of matter and energy.
pigment A material, like the natural colorings in skin, that alter the light reflected off of an object or transmitted through it. The overall color of a pigment typically depends on which wavelengths of visible light it absorbs and which ones it reflects.
satellite A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.
smoke Plumes of microscopic particles that float in the air. They can be comprised of anything very small. But the best known types are pollutants created by the incomplete burning of oil, wood and other carbon-based materials.
technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.
transparent Allowing light to pass through so that objects behind can be distinctly seen.
U.S. Geological Survey (or USGS) This is the largest nonmilitary U.S. agency charged with mapping water, Earth and biological resources. It collects information to help monitor the health of ecosystems, natural resources and natural hazards. It also studies the impacts of climate and land-use changes. A part of the U.S. Department of the Interior, USGS is headquartered in Reston, Va.
ultraviolet A portion of the light spectrum that is close to violet but invisible to the human eye.
vertical A term for the direction of a line or plane that runs up and down, as the vertical post for a streetlight does. It’s the opposite of horizontal, which would run parallel to the ground.
water vapor Water in its gaseous state, capable of being suspended in the air.
weather Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.
NASA Earth Observatory: When the dust settles
United Nations, Framework Convention on Climate Change: Women-led fog harvesting for a resilient, sustainable ecosystem