Clearing up the physics of clouds
Jacob Fugal has his head in the clouds these days. He studies them minutely and, beyond a shadow, is on the cutting edge of cloud physics.
He and other Michigan Tech researchers challenge the canonical view as they learn how clouds work, especially how they precipitate. The inquiry will enhance the understanding of the earth’s climate, what Fugal calls “the earth’s energy budget”—how much sunlight comes in and where it goes.
Clouds are either a blanket that holds warmth on the earth’s surface, or they are a reflector that bounces solar heat back into space. Thus, one of two scenarios might play out.
If the global temperature goes up, warmer clouds might be drier, less likely to precipitate, and die faster—so that more solar radiation reaches the earth, which warms it up even more. Or more water might evaporate and create more clouds that last longer and scatter the sun’s radiation—so that less solar radiation reaches the earth, which cools the earth.
“So,” says Fugal, “because of clouds, it could be global warming or global cooling. Because of that, we really need to know what clouds do, how long they last, and how they precipitate. The biggest uncertainty in how well we can predict global warming and climate change is clouds.”
Clouds are comprised of suspended water and ice; fueled by water vapor that rises from earth’s surface.
That vapor carries tiny particles of dust, salt, and organic compounds called aerosols. When they reach a point cold enough—the bottom of a cloud—tiny water droplets condense on these particles. Condensation releases heat, so the particles rise and grow in two different ways: by continually condensing (the higher they rise, the colder it gets, the more humid it is, and the more condensation occurs); and by colliding with each other and coalescing. At the top of the cloud, these water droplets freeze into ice crystals that, when heavy enough, fall, warm, melt, and become rain.
Fugal says that the textbook summary of how clouds precipitate hinges on completely still air, a situation he calls “quiescent.” In this simple system, bigger droplets fall faster than smaller droplets and occasionally unite.
Tech researchers look at fist-size pieces of clouds, and they are gathering evidence that the clouds’ many vortices and eddies affect how they precipitate.
With turbulence, the rising and falling of particles still happens, but, in addition, the air swirls and spins and flings water drops and ice crystals about—as though by a slingshot—and they tend to cluster outside the vortices, where they’re more likely to collide, grow, and fall.
With the exception of thunderstorms—and Fugal says cyclones, typhoons, and hurricanes are “organized systems of thunderstorms”—the turbulence inside those clouds is not intense; he compares it to the power of “a fan blowing in your face.”
“What’s amazing about a cloud,” Fugal adds, “is that you only have to change it a little bit before a lot changes. That’s the picture—a butterfly waving its wings in Brazil has an effect on the monsoons in the Philippines. That’s not literally true, but when there’s a little change in clouds, the effect is significant. Understanding them can improve our lives through better measurements, forecasting, and understanding of climate.”
Fugal earned his PhD in Physics at Michigan Tech in December 2007. His advisor was Associate Professor Raymond Shaw. Fugal already has made a contribution to his discipline. He designed and used a probe fitted on the wing of an airplane that uses holography to analyze tiny ice particles. He will continue the work as a postdoctoral fellow at the prestigious National Center for Atmospheric Research in Colorado.
Stronger Bones From the Lab?
Human bones are the framework for Matthew Barron’s inquiry and imagination. A biomedical engineering graduate student, Barron (left) dreams of growing bone in a laboratory and implanting it in people to repair broken and diseased bones.
That capability would improve upon the current practice of taking a bone from, say, the hip and using it elsewhere in the body.
Barron’s doctoral work, in its second year, builds on what is "long-known" about bones: disuse can weaken them; mechanical stimulus helps keep them healthy and functional.
"If you took [tennis player] Roger Federer and X-rayed his two arms," Barron explains, "his hitting arm would be way bigger—just because of the continual mechanical load."
But there are aspects of this phenomenon that scientists don’t understand and that drive Barron’s work, which is supported by the National Science Foundation. Can you overload the cells of a bone? Is there an optimal load? Should the load be constant or periodic?
Further, previous research has shown that bone cells can desensitize themselves to loading—thus, how do scientists know when the load is too much of a good thing?
"Down the road, people are going to want to grow bone outside of the body and implant it in the body," Barron says. "We have to understand the bone growth to produce replacement tissue."
The inquiry, under the guidance of Associate Professor Seth Donahue, might have a flip side: understanding and preventing bone disease. "Figuring out how bones grow might shed light on what isn’t happening in some diseased states, such as osteoporosis. Why isn’t bone being produced?"
Barron works with mouse bone cells and uses fluids to apply the load. "This is neat stuff," he says.
The prospects are a dream at this point, but they give him purpose and direction. He says of engineering in general and his field in particular: "Working on computers and cars is great. But being able to help somebody, that is a lot more important to me."
In 2004, Valerie Fuchs had a watershed experience. After her senior year of college, she traveled to Mississippi with Habitat for Humanity. She encountered "a very poor town in one of the poorest counties in the US."
There was no wastewater treatment and the water quality was poor—sewage went from homes to ditches, and then, during floods, from ditches into the Mississippi River. "It was something I didn’t think existed anymore in the US. I thought, 'I want to do something about this because it’s not good for the environment, it’s not healthy, and it’s not just.’"
She decided to pursue a career in water quality and sanitation and came to Tech for graduate study in environmental engineering.
Now beginning her PhD, she is under the guidance of Professor James Mihelcic and Associate Professor John Gierke. Supported by the National Science Foundation, she is addressing the effectiveness of nature-based, sewage treatment processes—such as engineered wetlands—for use between large-scale, urban treatment plants and small-scale, rural septic systems.
Engineered wetlands, lined with plastic or clay, are artificial swamps or marshes, and they use plants, soils, and bacteria to break down pollutants and clean up the water.
There are two types of engineered wetlands: those that flow horizontally for storm runoff and those that flow vertically, introducing the wastewater from the bottom up or the top down.
Fuchs has set up a laboratory system to assess the effectiveness of both—designing them for individual homes or clusters of up to two hundred homes.
The work has urgency, Fuchs says. "A Congressional study reported the water and wastewater infrastructure in the US is getting too small, deteriorating, and past its design life. There needs to be a lot more money and resources to develop new water distribution and wastewater treatment around the US."
She notes that a quarter of wastewater treatment in the country is septic systems—some "are not well monitored and not meeting treatment requirements."
Thus, the need for some smaller, more-natural systems that take wastewater, treat it, use it for irrigation, and release it back into the groundwater with a clean bill of health.
In striving for these improvements, Fuchs says she designed her research program to fit her own interests. And she loves Michigan Tech. "I can’t imagine a better place."