Stories tagged Forces of Nature

Nov
15
2006

Storm chasers know that puffy cumulus clouds often cause sudden rainstorms, while storms associated with stratus clouds form more slowly. Now physicists at England’s Open University have finally found an explanation.

They propose that neighboring water droplets in a stable stratus cloud don’t crash into each other because they’re all moving at about the same speed. But fast-forming, turbulent cumulous clouds contain water droplets moving at many different speeds. They crash into each other and form larger drops. As the turbulence grows, the drops grow quickly and fall as rain within a few minutes.

Cumulous cloud: These puffy clouds are associated with sudden rainstorms. Scientists are beginning to understand why.
Cumulous cloud: These puffy clouds are associated with sudden rainstorms. Scientists are beginning to understand why.

Sun and rain
Ever noticed the bright, moving lines on the bottom of a stream, bathtub, or swimming pool? They’re called caustics, and they’re caused when ripples on the water’s surface focus sunlight. (Caustics form whenever light rays are bent by a curved surface or object and then projected onto another surface.

Caustics have a characteristic shape. Physicists can graph the phenomenon mathematically, and the graph also describes other phenomena, such as particle motion or the movement of raindrops within a cumulus cloud.

Caustics: What do the rippling patterns on the bottom of a swimming pool and cumulous clouds have in common? (Photo by R. Motti)
Caustics: What do the rippling patterns on the bottom of a swimming pool and cumulous clouds have in common? (Photo by R. Motti)

Atmosphere to outer space
The researchers say their finding won’t have any impact on weather forecasting. But particle collisions in turbulent gases must have been involved in planet formation. Perhaps the same theory can be applied?

If you're at the museum on Saturday afternoon (11/18), the MakeIt team can help you play with caustics. Does bending mylar in a different direction produce a new pattern? Does using a different color flashlight or a brighter or dimmer light affect the design?

You can also play with caustics at home.

Sep
01
2006

Farming the Wind: photo by Dirk Ingo Franke.   licensed under Creative Commons Attribution ShareAlike 1.0
Farming the Wind: photo by Dirk Ingo Franke. licensed under Creative Commons Attribution ShareAlike 1.0

Is wind a good cash crop?

At the State Fair I observed as several farmers were researching whether a 1.5 million dollar wind turbine would make them money. The biggest factor was how much wind was available where they lived.The break even point was if they had better than 7.5 mph average wind speeds( see map pdf). Apparently several banks and also John Deere are financing projects if the numbers look good. Power companies will give a 20 year contract to buy electricity. The wind generators usally have a life expectancy of 25 years. Most farmers pay back the loan in ten years, then can reap profits of over $100,000 a year for the next 15 years. Sounds tempting, doesn't it?

An Iowa company hopes to build a $200 million wind farm.

Iowa Winds LLC hopes to build a 200- to 300-megawatt farm covering about 40,000 acres in Franklin County.

Company officials said the farm could be the nation's largest -- depending on the permits and the county's power grid infrastructure. If the county approves the project, construction would start next spring and take about a year, said Franklin County Supervisor Michael Nolte. LiveScience

Texas leads the nation with 2,370 megawatts of wind energy installed and California has 2,323 megawatts (American Wind Association). Iowa is in third place with 836 megawatts. Minnesota is fourth with 794 megawatts. The total United States capacity is about 10,000 megawatts. These numbers and rankings are changing. Wind energy output is growing by about 30 percent a year globally.

Want more? Go to the Minnesota Dept. of Commerce wind energy information web page.

Mar
08
2006


Sumbawa: A map of Indonesia, showing the location of Sumbawa Island.

Scientist working in Indonesia have
found the remains of a civilization wiped out by a volcanic eruption.

Mount Tambora's cataclysmic eruption on April 10, 1815, buried the inhabitants of Sumbawa Island under searing ash, gas and rock and is blamed for an estimated 88,000 deaths. The eruption was at least four times more powerful than Mount Krakatoa's in 1883.

Interestingly, the culture wiped out by the explosion was very different from others in the area. Based on the language they spoke, some scientist had speculated these people originally came from Indochina. (Other Indonesian cultures are believed to have come from south China, via Taiwan and the Philippines.) The archaeologists have dug up pottery similar to that found in Vietnam, strengthening the possibility of a connection.

Dec
31
2005

A popular song from the musical RENT says there are 525,600 minutes in a year. That answer is right for most calendar years (including 2005 and 2006). A leap year (with February 29 tacked on) has 527,040 minutes. But the time it actually takes the Earth to travel once around the Sun is about 525,948.76 minutes. (That translates to 365 days, 5 hours, 48 minutes, and 46 seconds.)

Mar
04
2005

There is probably no day greeted with greater joy and anticipation than the first day of spring -- especially after a Minnesota winter! Sometimes, the only thing that gets us through February is knowing that better days are on the way. But when, exactly, does spring get here?

TV weathermen will tell you that spring starts on the vernal equinox -- the day when the number of hours of daylight are equal to the number of hours of night. (In 2005, this falls on March 20.) The problem is, the weathermen are wrong.