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Happy Thanksgiving

11/24/2022

Our Nonfiction Minute authors wish all of you a wonderful Thanksgiving holiday.

We will not be posting Minutes for the rest of the week, but will return on Saturday morning, December 3 with a post for the week of December 5. If you want to find some Minutes you might have missed or are looking for some interesting family dinner conversation, try browsing through our archives. You can access them by topic or author from the list on the right, or by month by scrolling all the way down to the bottom of the Topics and Authors list.

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Earth's Emergency Heat Valve: The Hurricane

11/23/2022

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Vicki Cobb
The Master Chef of Kids' Hands-on Science

Earth has a problem. The sun creates hot spots over land, in the air and in the water. That’s why there are winds, weather, and currents in the ocean as Earth tries to even out the heat, moving warmer masses of air and water to cooler areas.

During hurricane season ( from June 1-November 30), only 10 or 11 of the 80 tropical disturbances off the west coast of Africa (where most of our hurricanes originate) become large enough storms to be given a name. Only two or three of them hit the United States. They are not frequent but they are massive wind storms that can destroy life and property.

Do they do anything good at all? As far as the Earth is concerned, these largest of all storms are a safety valve to rapidly move heat that has been accumulating in the oceans up to the stratosphere (from 7 to 31 miles above the Earth’s surface). From there it will be transported through the air to over the North Pole. It’s the way Earth stops a fever.

Once a hurricane forms, it must have an ocean surface that is at least 80°F to keep moving and to grow. Under the storm, huge amounts of warm water become water vapor. Warm moist air rapidly rises through the spinning winds of the hurricane, up to the stratosphere. When moist air reaches the frigid (-70°F) stratosphere the water vapor quickly condenses to liquid water (rain) releasing its heat. This heat makes surrounding air molecules move faster forming winds.

How do hurricanes cool off the oceans? How do they move the heat? Here’s a clue: Wet your finger and wave it in the air. How does it feel? Pretty cool, I bet! That’s because the heat from your finger changes liquid water into water vapor (a gas) as your finger dries. Water vapor molecules store this extra heat. They rise because they are lighter than other air molecules.

So, a hurricane is a heat engine that moves water vapor from the ocean’s surface high enough to condense back into liquid water and release heat safely to the stratosphere forming rivers of wind that move it to the poles.

Scientists predict that global warming will increase the number and the power of the hurricanes as the ocean surfaces become increasingly warmer during our summers.

This diagram of the anatomy of a hurricane shows the direction of the winds. The blue represents cold air descending while the pink shows warm moist air rising. The outflow surface clouds form as water condenses into a "table-top" cloud, releasing heat that becomes wind. Kelvinsong via Wikimedia

Hurricane Isabel (2003) as seen from orbit during Expedition 7 of the International Space Station. The eye, eyewall, and surrounding rainbands, all characteristics of hurricanes, are clearly visible in this view from space. Image courtesy of Mike Trenchard, Earth Sciences & Image Analysis Laboratory, NASA Johnson Space Center

Vicki Cobb's How Could We Harness a Hurricane? offers questions and provides new points of view that may just change peoples' thinking by showing young readers the work scientists and engineers are doing to avoid future disasters. The book includes hands-on experiments that make science fun, be it at home or in the classroom. Here's a link to the book' s Trailer.

How Could We Harness a Hurricane was named a 2018 Best STEM Book K-12 by the National Science Teachers Association and the Children's Book Council.

Vicki is a member of iNK's Authors on Call so you can invite her to your classroom via iNK's videoconferening Zoom Room. Click here to find out more:

MLA 8 Citation
Cobb, Vicki. "Earth's Emergency Heat Valve: The Hurricane." Nonfiction Minute,
iNK Think Tank, 24 Apr. 2018, www.nonfictionminute.org/
the-nonfiction-minute/Earths-Emergency-Heat-Valve-The-Hurricane.

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Amazing Maize

11/23/2022

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Dorothy Hinshaw Patent

Nature's Animal Ambassador

If I asked you what grain is the most harvested in the world, you’d probably answer either wheat or rice. But the answer is actually corn, more accurately called ‘maize.’ This nutritious crop that originated in Mexico feeds not only people but also animals around the world. We’re used to the wonderfully tender sweet corn harvested in late summer and early autumn, but most maize is actually field corn, more starchy than sweet and used as animal feed or to make cornmeal and flour.

For a long time, biologists puzzled about the origins of this important crop. There is no wild plant that looks anything like modern corn, which is actually a giant grass. The closest relative is a scrawny branching plant with hard dark seeds called teosinte. It seems a huge jump from teosinte to corn, yet geneticist George Beadle found in the 1930s that corn and teosinte have the same number of chromosomes and could be crossbred to produce hybrids. With the limited tools available at that time, Beadle deduced that only about five genes were involved in creating the differences between teosinte and corn.

Fast forward to modern times, when scientists can look directly at DNA and analyze every detail of its structure. We now know that Beadle came very close to the truth—about five regions in the DNA seem to control the major differences between teosinte and corn. For example, these two plants look so very different, yet just one single gene turns a branched plant into a single stalk, like a stalk of corn. Another single gene controls one of the most dramatic and certainly most important traits for farmers—the nature of the seeds and their stalk. In teosinte, each seed has a hard covering. Just one gene eliminates the hard covering and produces a stalk bearing exposed seeds, like an ear of corn.

Scientists now use maize as a perfect example of two major ways evolution happens. One way is through major sudden jumps, like the change from a branching plant to a single stalk. The other is the more gradual kind of change that has led to the thousands of different kinds of maize grown by farmers today. There are probably hundreds of varieties of sweet corn and thousands of varieties of field corn. Think about that the next time you bite into a nice crunchy taco made from a corn tortilla.

Here you can see the major differences between a teosinte plant and a corn plant. Credit:TeosinteCornUOR

Corn was a very important crop for homesteaders in the American West, used both to feed themselves as well as their animals. Read about it in Homesteading: Settling America's Heartland, revised and expanded edition, Mountain Press, 2013.

Dorothy Hinshaw Patent is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Patent, Dorothy Hinshaw. "Amazing Maize." Nonfiction Minute, iNK Think Tank, 8
June 2018, www.nonfictionminute.org/the-nonfiction-minute/Amazing-Maize.

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How Skunks Play Fair

11/17/2022

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Are skunks aggressive, dangerous animals? Or are they peaceful animals that try to avoid trouble? Well, biologists who study skunks think of them this way: if life were a sport, skunks would be known for their strong defense and for playing fair.

Skunk stinkiness comes from a chemical weapon called musk. Foxes, weasels, and some other mammals also produce musk, but skunk musk is especially strong and long-lasting. And only skunks use musk to defend themselves from attack.

Picture a skunk ambling along in the night, looking for food. It digs in the soil to get tasty earthworms and beetle grubs. The black and white fur that comes with just being a skunk sends a warning. This color pattern is unusual among mammals. It signals: "Beware, don't mess with me!"

Suppose a coyote or other predator ignores this first warning. It steps toward the skunk. When a skunk feels threatened, it faces the danger. It raises its tail and tries to look as big as possible. It stamps its feet and clicks its teeth together. It may growl or hiss.

Oh, oh! Despite all of these warnings, the coyote growls and comes closer. Now the skunk gets really serious. It twists its body into a U-shape, so it can see the coyote and also aim its rear end toward it. The skunk's tail arches over its back, away from its rear—the final warning. This gives the skunk a clear shot, and also protects its own fur from the stinky musk. Skunks try to avoid smelling bad!

From two grape-sized glands, a skunk can spray musk as a fine mist, or squirt a stream. It can squirt accurately for about 12 feet (3.7m), and hit an attacking animal right in the face. The musk stings the predator's eyes, and can blur its vision for a while. And it stinks! Animals hit with this musk learn to never bother a skunk again.

A skunk's glands store enough musk to fire a half dozen shots but then need a week or so to produce more. This is seldom a problem, since a skunk sprays only when its life seems to be in danger. Some skunks can go for months or even years without spraying musk. That's fine with them. Skunks want to avoid trouble, and "play fair" with their many warnings.

A skunks’s stripes point to where the spray comes out. A 2011 study found that animal species that choose fight over flight when faced with a predator often have markings that draw attention to their best weapon. So while a badger has stripes on his face to highlight his sharp teeth, skunks’ stripes are perfectly positioned to highlight their ability to spray potential threats. By http://www.birdphotos.com via Wikimedia Commons

Skunks are so nice that some people want to keep them as pets. The striped skunk is the most social skunk and the one most commonly domesticated. The legality of keeping skunks as pets in the US varies by state, with it being illegal in a majority of them. By Matt MacGillivray via Wikimedia Commons

Larry Pringle has written many animal books, among them The Secret Life of the Red Fox. His The Secret Life of the Skunk was published by Boyds Mills Press in 2019. It is about spring and summer in the lives of a mother striped skunk and her kits.

ML 8 Citation
Pringle, Laurence. "How Skunks Play Fair." Nonfiction Minute, iNK Think Tank, 8 Nov. 2017, www.nonfictionminute.org/how-skinks-play-fair.

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Happy Thanksgiving

Earth's Emergency Heat Valve: The Hurricane

Amazing Maize

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