Chapter 14
Try This at Home
In This Chapter
Becoming weatherwise
Following George, Tom, and Ben
Making rainbows and clouds
Bending the light
I t’s your weather, you know. Just because you can’t control it doesn’t mean it’s not yours. (Hey, nobody else can control theirs either!) The rainbow, the cloud, the sunset — nobody else sees it from exactly the same angle you do. The snow and the rain that falls on your face and even the cool summer breeze that you feel on your arm — that’s all yours.
You can take a personal interest in your weather, if you want to. A lot of famous and darn smart people have done just that over the years. In this chapter, I show you how to get started keeping track of your weather. I tell you about some of the great “amateur” weather-watchers in history and some of the great things they did. Also in this chapter are some cool experiments you can do to test some of the basic ideas about how weather works.
You’re Not Just an Amateur
Amateur is a word that has fallen on hard times, especially in the sciences. Somebody pays a professional, while an amateur is, well, just an amateur. There’s a good reason for this. After all, when I listen to a weather forecast, I want to know that this opinion about what it’s going to be like tomorrow is coming from a pro. Still, amateur deserves more credit than it gets.
Long before there were national weather services, keeping an eye on the weather was just something smart people did. Weather watching was an important part of exploration. When they arrived in the “new land” of North America, for example, early settlers from Europe realized very soon that just to survive the difficult winters they were going to have to keep their wits about them and their eyes on the sky.
Even now, while forecasters use very fancy supercomputers, still they rely on weatherwise amateurs. National weather services around the world use large networks of amateur weather observers. They get daily records of rainfall and temperatures from people in places that are hard to get to, and they depend on spotters for eyewitness accounts of tornadoes and other extreme weather events.
If you are keeping an eye on the sky, you are part of a tradition that is older than the United States. George Washington kept a weather diary even before the Revolutionary War. And Thomas Jefferson took time out from writing the Declaration of Independence to go get his first thermometer. And Benjamin Franklin was one of the most famous weather amateurs of all. When you watch the weather, no matter how you do it, you are following in some big footsteps, and you are following some good advice.
“Some people are weatherwise,” Ben Franklin said, “but most are otherwise.”
Galileo and the Boys
A lot of people have expressed a lot of opinions about the weather for ages and ages. It seems fair enough. Since everybody has to put up with the weather, everybody can have their say. For the longest time, listening to stories and opinions was about all there was to studying weather. A lot of interesting “weather lore” and proverbs have been passed down, but they are not what science is all about.
Galileo’s thermometer
Credit for inventing the thermometer goes to the great Italian mathematician and philosopher Galileo Galilei. (This is the fellow who got into a lot of famous trouble with the Catholic Church for insisting that the Sun does not revolve around the Earth — that it’s the other way around.)
In 1593, Galileo kept in his library a glass bulb about the size of a chicken egg with a clear thin tube sticking out of it so that he and his friends could watch the liquid inside the tube rise and fall as the temperature changed. The volume of the liquid expands when it warms up, he figured, and shrinks back when it cools.
Galileo had a lot of things going on — inventing the telescope, checking out sunspots, his teaching jobs, and the trial by the Inquisition. Meanwhile, other scientists picked up and ran with the thermometer idea. It took them a number of years to perfect the instrument. (It took the Catholic Church a number of years to admit that it was wrong about Galileo. The official apology came from Pope John Paul II in 1992.)
Torricelli’s barometer
One of Galileo’s students, Evangelista Torricelli, invented the barometer. He took a tube about four feet long, filled it with mercury, plugged one end to make a vacuum, and sank the open end in a pool of the liquid metal. He noticed that the mercury ran down the tube, but only so far, and then it abruptly stopped, always at the same spot on the tube.
A French fellow, Blaise Pascal, figured out that weather changes could be causing the mercury in Torricelli’s barometer to go up and down.
Cardinal de Cusa’s hygrometer
People have always known that the air sometimes feels especially wet and sometimes feels especially dry, even if they didn’t always know what to make of it. The first person to devise a way to measure the moisture in the air was a German fellow clear back in the 1400s, Cardinal Nicholas de Cusa.
Hang a big bunch of wool from one end of a rod, he said, and balance it with rocks at the other. The wool will absorb moisture from the air, and that end of the rod will go up or down depending on how wet or dry it is. It took a long time and many people to make an instrument that would accurately measure the humidity in the air, but de Cusa had the idea.
The most accurate hygrometers today work on a similar principle, except that they use human hair instead of wool. A strand of hair stretches as it absorbs moisture, and its change in length is measured on a dial.
Early American Weathermen
Even before the nation was born, the colonists from Europe were getting up close and personal with the weather. The English especially were very surprised — and disappointed — to learn that the winters in the New World were much more severe than the same seasons in Europe. The thinking at the time was that regions at the same latitude, or distance from the Equator, all had the same climate.
They didn’t expect the cold that killed all but 32 of the original 105 colonists at Jamestown, Virginia, that first winter in 1607, and all but 50 of the original 102 pilgrims at Plymouth, Massachusetts, in 1620. And the pilgrims hadn’t counted on hurricanes wrecking their supply ships.
Christopher Columbus was lucky he did not encounter a hurricane on his first round-trip in 1492. After all, a journey reaching land on October 12 would have crossed the Atlantic during the heart of the hurricane season. On later voyages, he did encounter hurricanes and was lucky again to survive. Some others who followed him were not so lucky.
The first careful, routine weather observations in North America were made in 1644 by a Lutheran minister, the Reverend John Campanius Holm, near what is now Wilmington, Delaware. Many early weather observers were ministers, and the theme of many sermons was how the latest storm was an act of God.
Personal weather watching was worthwhile and interesting business in the old days, and it still is. Some of the people who were busy putting the United States together as an independent nation took the time to watch and study what was going on in the sky over their heads.
George did it
George Washington kept a daily weather diary until December 13, 1799. His notations about the snow and the wind and the cold apparently were the last things he wrote. In fact, weather may have contributed to his death. He fell ill with a throat infection suddenly after riding around his farms in the cold weather he wrote about and died the next day.
Washington learned the importance of weather early in his career. In 1753, during his first military mission at the age of 21, the winter weather was so bad that it almost brought an early end to his military service — and his life.
More than once, General Washington used his skills as a weather forecaster to great advantage in his battles against the British during the Revolutionary War. On January 2, 1777, Washington found his troops trapped. On one side was mud, on another an icy river, and on another, the British. But a northwest wind was blowing, and Washington knew the mud would freeze. At midnight, his troops were able to retreat across the mud to safety. Again in the winter of 1778, Washington led a successful surprise nighttime attack against General Cornwallis’ troops over muddy ground that had frozen in the chill of a northwest wind.
Tom did it
Thomas Jefferson took a break from writing the Declaration of Independence to go buy his first thermometer, and soon afterward he got himself a barometer. Jefferson collected weather information everywhere in the country he could find it. He exchanged letters with people far and wide about the weather in their regions. He kept a record of the weather around him every day for 50 years.
It was Jefferson who first realized the value of taking weather observations at different locations at the same time everyday. He exchanged letters with a fellow in Williamsburg, Virginia, and compared their 4 p.m. temperature, air pressure, and wind measurements over six weeks in 1778. What he discovered surprised him: The climate was cooler in his mountain home in Monticello than the Virginia lowlands of Williamsburg.
Jefferson was considered an expert on American weather and climate. He always argued that what the country needed was a network of weather observers. When he was president, the Lewis and Clark Expedition headed out on its long exploration of the Pacific Northwest, and Jefferson made sure that they took along accurate weather instruments.
Ben did it all
Benjamin Franklin, among other things, was a pioneer in important weather science. In his library, he had five thermometers and a barometer.
His most famous weather experiment — flying a kite in a thunderstorm to confirm that lightning was an electrical charge — was valuable but extremely risky business.
.jpg)
Franklin also was the first person to realize that the winds that make storms travel from one place to another are not the same winds that the storm blows in your face. Chapter 8 details his thinking about the storm that clouded over his plans to view an eclipse of the moon. Exchanging letters with his brother in Boston, Franklin figured out that although the storm was blowing winds from the northeast, other winds were carrying the storm itself to the northeast.
This idea takes a little getting used to. Feeling the northeast wind of a powerful winter nor’easter, for example, you might feel sure that the storm is coming at you from out of the northeast. But the fact is, as Franklin observed, nor’easters come up the East Coast from the south.
He was first to suggest that the eruptions of volcanoes affected the weather by cooling the atmosphere. He told scientists in England that he thought the unusually cool summer in Paris in 1783 was the result of an erupting volcano.
And Franklin was first to study the Gulf Stream, the warm ocean current in the North Atlantic that Chapter 4 describes, which is especially important to weather in the eastern United States and in Europe. Modern weather scientists are still studying the Gulf Stream.
Watching Your Weather
Watching weather is an even older tradition than talking about it, if you can imagine that. And it’s just as much fun as it ever was. You can watch weather in a lot more ways now — more fancy instruments to read, more things to buy, and a load of stuff to check out on the Internet about the weather. But the fancy way is not always the best way when it comes to weather (and a lot of other stuff), and in fact, the most satisfying may be the least fancy approach.
Do you live in an area where volunteer storm spotters are used to help keep track of such things as tornadoes and other weather events that are hazardous to public safety? Check it out with your nearest National Weather Service office or your local emergency management agency.
Getting Fancy
If you want to get fancy observing weather, you can get as fancy as your ambition will reach and your pocketbook will allow. You can observe the weather with the instruments and the techniques that experienced weather observers have always used, or you can take advantage of the electronic age and rig any number of gadgets to a home weather station. Fancy or not, no weatherwise home station is complete without an NOAA Weather Radio, which Chapter 1 describes, to provide vital information during weather emergencies.
Going instrumental
If you have the room in your yard, you can rig up an instrument shelter and keep more elaborate records. You can keep records for a period of time and put them in a spreadsheet or database program on your computer. And then you can compare your results with the records kept by nearby National Weather Service observing stations.
An instrument shelter (see Figure 14-1) is a big white box about four feet off the ground that has slatted sides to protect the instruments inside from direct sunlight but to allow air to move freely around the instruments. It has a double roof to prevent the Sun’s radiation from heating up the box.
|
Figure 14-1: An instrument shelter at a cooperative weather station in Granger, Utah, about 1930. |
|
National Oceanic and Atmospheric Administration/ Department of Commerce.
The shelter contains these instruments:
A wet-bulb thermometer: A wet-bulb thermometer is a well-ventilated thermometer surrounded in wet muslin that gives you the temperature of air that is saturated in water vapor.
A dry-bulb thermometer: A dry bulb thermometer measures the actual air temperature.
A maximum temperature thermometer: The maximum thermometer is designed so that it keeps track of the highest temperature reached that day.
A minimum temperature thermometer: The minimum thermometer is rigged to mark how low the temperature fell.
An aneroid barometer: The aneroid barometer is a more convenient mechanical version of a mercury barometer that measures air pressure on the face of a dial rather than heights of liquid in a tube.
Going digital
If you like electronic gadgetry, boy, did you come to the right hobby! All of the essential weather measuring instruments — as well as nonessential instruments — are available in digital gear. They range widely in precision and in price.
Instruments can be purchased as single-service components of a self- assembled home weather station. Others are designed and packaged as integrated home weather stations. Prices for electronic home weather stations range from under $250 to well over $2,000. Many come with consoles, which permit them to connect directly to a desktop computer, and have their own software for storing and graphically portraying information.
Other electronic devices and services allow you to keep up to the minute with changing weather conditions. You can be alerted by beeper or Internet-linked cellular telephone any time a storm alert is issued or a forecast is changed.
A wide range of computer software is available through software vendors and instrument retailers as well as archives over the Internet. The Appendix gives you a good idea of the huge number of weather-related resources available on the Internet. Computer users will find software available for any number of applications. They can fashion their own forecasts, for example, or use their systems to maintain constantly updated information about local weather conditions.
Cool Weather Experiments
A weather scientist by the name of Zbigniew Sorbjan at Marquette University in Milwaukee, Wisconsin, has written the book on the subject of cool weather experiments. The title of the book is Hands-On Meteorology, and it’s published by the American Meteorological Society. Here are some well-known weather experiments you can try at home.
Making rainbows
Want to make a rainbow?
Technically speaking, you can’t really make a rainbow unless you can make it rain. But I’m not going to get too technical about this. The colors of the rainbow are always hidden in the white sunlight unless something happens to make its different wavelengths separate from one another. As Chapter 13 describes, the different wavelengths appear to your eyes as different colors.
With a spray from a garden hose, you can come pretty darn close to copying what it takes to make one of the most beautiful effects in nature. You’ve got the basic ingredients for a rainbow — the Sun at your back, and the falling drops of water in front of you. Make sure that the spray is below your eye level. The colors will show up in a semicircle band in the stream of water. Now change the spray coming out of the nozzle so that it comes out in bigger and smaller droplets of water. The rainbow changes brightness and width just like it does as sunlight is bent by different sizes of falling raindrops.
Here’s an easy one to try inside. Fill up a jar with water and place it on the window sill so that the Sun shines down through it. Then place a sheet of white paper on the floor so that the light passing through the jar shines on the paper. The water jar should bend the different lengths of light waves as they pass through the jar and spread them out in the colors of the rainbow on the sheet of paper.
Go Figure Academy of Sciences bites the dust
I was planning on having my people at the Go Figure Academy of Sciences come up with some really cool experiments about the weather. It was going to be great. You know, lightning, thunder, the works. But that’s not going to be possible now.
I kind of lost control of my people after I had them try to chase down the end of a really nifty-looking rainbow in New Jersey to check out the pot-of-gold idea. They all came back muddy and
mad at me. You might say the climate of the place completely changed. Still, I figured I owed it to you, to make sure about the gold. And besides, what if there had been gold? You know, running an academy of sciences is expensive, even one I made up, and I could have used the dough.
Anyway, to make a long story short, the whole ungrateful bunch of them has gone back to the Massachusetts Institute of Technology. Go figure.
Bending light by refraction
Want to bend some light?
It’s easy to see light bend as it passes through materials of different density. Turn the lights out and shine a flashlight into a glass of water. If you point the beam straight down into the water, its path is straight. But shine it at an angle and watch the light rays bend downward in the glass. The light waves are changing speed as they go from the air into the thicker, denser liquid. And the speed change is what gives them the bends.
Here’s another light-bending trick with a glass of water. Turn the lights on and stick a pencil in the water. Move the pencil closer to you and then farther away from you and watch the submerged image of the pencil become thicker and thinner. That’s the curved shape of the glass changing the amount of water the image of the pencil is traveling through, causing the light waves to spread out one way and come together another.
Bending light by diffraction
Want to see what it looks like when light waves bump into each other?
Here’s an optical effect at your fingertips. Well, more exactly, between your fingers. Look through the beefy parts of your first and second fingers, letting just enough light through to see, and you will notice dark lines running through the image you see. It looks as though you are seeing the world through a set of window blinds. This is the effect of light bending through the tiny space on the way to your eyes, just as it does when it passes through the gaps between water droplets to form coronas, or between raindrops as part of rainbows. The dark bands are where the wavelengths of light interfere with one another in a way that they cancel each other out.
Weighing in on air
Want to prove that air has weight?
You and I know that air has volume — takes up space — without even thinking about it. That’s what balloons are about — air taking up space inside them. And cars move around on cushions of air that take up space inside rubber tires.
To show that air has weight, you need two balloons, a rod, and some string. Blow up each balloon to the same size so that each contains the same amount of compressed air. Then tie them to each end of the rod with the same length of string. Now attach a length of string to the middle of the rod and adjust it so that the rod is straight across, so that the balloons are evenly balanced. Now pop one of the balloons and watch what happens to the rod. It will droop down on the end that holds the inflated balloon.
This is similar to the experiment that Galileo Galilei did in 1638. He pumped a lot of air into a glass flask and weighed the flask very carefully before and afterward. When the compressed air was in it, the flask was heavier. But many people laughed at Galileo about this for years afterward. Any fool could see that air had nothing in it to weigh!
Of course, proving that air has weight is not the same thing as finding out the weight of air. That took some fancy figuring many years later with some sensitive instruments to get just right. So, how much does air weigh? At sea level, a cubic yard of air — about 202 gallons of the stuff — weighs about 2 pounds.
Testing the pressure
Here’s a way to get the idea of how air pressure changes with height, although this experiment involves water.
Take a soda can or some other fairly good size container that you can punch holes into. With something like a nail, put one hole maybe a third of the way down from the rim of the can and another whole quite a ways closer to the bottom of the can. Now fill it with water and look at the different shapes of the spouts coming from the holes. The top spout droops down more quickly than the spout coming out of the bottom hole, because the bottom has all the pressure of the water in the can pushing out, while the top hole has only the pressure of the water above it.
Now take another can and punch a few holes all at the same level, like down near the bottom. Pour water into this can and watch the spouts. Because they all have the same amount of water above them, they have the same pressure. So the spouts shoot out at the same curves and the same distance.
The greenhouse effect
Want to see what the “greenhouse effect” is about?
You need two thermometers mounted on two pieces of cardboard in a way that allows them to stand upright. Stand them side by side in a quiet sunny spot with their cardboard backs to the direct sunlight. Now place a large glass jar over one of the thermometers. Before long, you will notice that the thermometer in the jar measures a warmer temperature. The jar is acting like a greenhouse, preventing the warm air from rising away as it does around the other thermometer.
This is exactly like a greenhouse that a nursery uses. But it is not exactly the greenhouse effect that weather scientists have in mind when they talk about the atmosphere. A nursery’s greenhouse roof prevents air from circulating, for example, while under the atmosphere’s greenhouse gases, the whole world of weather is going on.
What weather scientists mean by the greenhouse effect is this: Some of the warmth from the Sun that is radiating up from the Earth in the form of invisible infrared rays is absorbed by these greenhouse gases in the atmosphere. So instead of escaping out into space, some of rays warm the atmosphere and some get sent back toward Earth. Like the greenhouse, the effect is that Earth is much warmer because of these gases in its atmosphere than it would be without them. (And a good thing too, by the way. Without this natural greenhouse effect, you and I would freeze to death down here!)
Cloud in a can
How about making a cloud?
You’ll need to fashion a device called a cold chamber. With a contraption not too much different from this, scientists first experimented with seeding clouds to produce rain.
You will need two cans, one very large (or a pail) and one smaller. Put some ice mixed with salt in the bottom of the larger can. Place the small can on the ice so that its top is level with the top of the larger can. Pack ice and salt in the space between the cans. The large can will grow very cold, so it’s a good idea to wrap a towel around it to protect your hands. Soon the air in the small can will become very cold. When you breathe into the small can, the cold will condense the water vapor in your breath into a cloud.
A bottle of fog
How about making a bottle of fog?
Fill a big jar with hot water, and then pour all of it out except for about an inch of water in the bottom. Now put a strainer over the top of the jar and put a bunch of ice cubes in the strainer. In a few minutes, the cold air from the ice cubes will sink down, and the air rising from the warm water in bottom will cause condensation to take place, just like Chapter 5 describes. What you have is a bottle of cloud, or fog.