Weather For Dummies. John D. Cox

to weather that I provide in this book, you get access to even more help and information online at Dummies.com. Check out this book’s online Cheat Sheet. Just go to www.dummies.com and search for “Weather For Dummies Cheat Sheet.”

Where to Go from Here

      Go outside. I mean it. You’ve been spending too much time indoors, anyway, so close this book temporarily, tuck it under your arm, and head out the door. Go outside and give your sky a good looking-over. It’s your sky, and it’s your weather, because nobody else sees it or feels it exactly like you do. Are there clouds up there? Do you know how they form or what their names are? Do you know how much fun it is to start practicing identifying the clouds in your sky? If you don’t, it’s time to come back inside and open Weather For Dummies again. Chapter 6 is a good place to start.

Part 1

      What’s Going On Up There?

IN THIS PART …

      Discover weather science’s most popular finished product: the daily weather forecast. See what goes into making state-of-the-art accurate forecasts and understanding how to interpret them.

      Wrap your mind around weather words — precipitation, temperature, humidity, highs and low, wind chill, among others — and what they mean in your local forecast.

      Find out about the things that make the atmosphere and its weather the way it is — so changeable — here today, gone tomorrow, as the saying goes.

      Find the answer to the question, “What is fog, exactly?” as well as how the oceans and the land masses affect your weather.

Chapter 1

      What in the World Is Weather?

      IN THIS CHAPTER

      

Looking at our imperfect planet

      

Exploring the weather forecast

      

Hanging with the weather celebrities

      Earth is not a perfect planet. (It may well be that none of them are, but, you know, who are we to say?) It is not perfectly round, for one thing. One half of it has a lot of land with mountains and valleys, the other half, not so much. It circulates (once a year) around the Sun, its energy-supplying star, but the path it takes is not perfectly circular either. It is not perfectly upright, for another thing, the way you might expect a perfect planet to be. In relation to the Sun, it is seriously akilter, spinning (once a day) on a 23-degree tilt, as if it has been knocked over by something. On top of everything is the atmosphere, this brew of nitrogen and oxygen and other gases that make up the air we breathe. This ocean of air swirls along like the planet itself — but not perfectly.

      All these imperfections create imbalances of heat and cold, wet and dry that keep the atmosphere in motion, like a soft body squirming in a hard seat. These motions of an uncomfortable atmosphere always looking for balanced perfection — this squirming, that’s what we call weather. It doesn’t just make life interesting, by the way; it supplies our fresh air and our fresh water. It makes life possible.

In this chapter, I give you a quick survey of the subject of meteorology — weather science — and where in Weather For Dummies you can find more information about each topic. Beginning with the product we encounter every day and moving on to explore how the atmosphere’s changing chemical composition is hitting the ground, let’s take a look at what’s in store.

The Daily Forecast: A Scientific Marvel

      Weather For Dummies begins with weather science’s most popular finished product: the daily forecast. Without all the numbers and equations, the first part of the book describes what goes into making a forecast and understanding what it means. It lays out the terms that apply and the circumstances that make up weather emergencies.

      Before we get into the details of the weather science behind it in Chapter 2, though, take a closer look at the next televised weather forecast you see. You will probably see a sharp, full-color image of half the Earth, captured in real time by a satellite that is constantly hovering 22,300 miles above the planet. You will see great arms and swirls of clouds crawling across the landscape, the signatures of storms. Even without explanation, you can see where the storms have been and surmise where they are going.

      This is a uniquely modern experience. Nobody before us has ever witnessed a more helpful or accurate prediction of the future behavior of the atmosphere. This short, precise presentation is an honest-to-goodness scientific marvel, the result of many years of demanding research and incredible expense.

      They make it look slick and easy on TV, of course — the smoothly moving images, the colorful animations driven by extremely high-powered computer models — but before that forecast got to the television studio, a lot of hard-knuckle science went into creating it. And hard-knuckle life. In 19th-century England, the first man to issue a weather forecast, Vice-Admiral Robert FitzRoy, an English officer in the Royal Navy, was pleading the case for so many sailors lost at sea. He didn’t succeed, but he died trying, and he left behind the popular idea that weather services are a government obligation.

The scientific knowledge that made modern forecasting possible did not come easily over the years. Earth does not very willingly give up her big secrets. During World War I, the young Englishman Louis Fry Richardson, a brilliant mathematician, described his impossible dream of a “forecast factory” — a multi-layered, gridded theoretical “atmosphere” tended by hundreds of individuals sharing data with others attending adjacent blocks of air. During World War II, a stable of brilliant scientists built the first electronic computer that was actually capable of such an ingenious, enormously complex undertaking. So, in the 1950s, began the new computer-driven era of “numerical weather prediction” and it changed everything.

      The advent of weather satellites in the 1960s made visually obvious to everyone what research meteorologists had been grappling with all along: weather’s natural enormity — the truly planetary scale of the problems they were trying to solve. (Chapter 16 delves into the forecasting work of satellites and other tools in the weather forecaster’s toolbox.)

What Causes Weather?

      So why is there weather? What basic forms does it take? Chapter 3 is where you find the answers to these questions. Sometimes it helps to think of the atmosphere as a blanket that has been thrown over the planet. The blanket’s surface is not entirely smooth. There are ridges and folds and bumps and dips here and there. This is where storms are, in these imperfections. Chapter 3 explains why there are storms and Chapter 4 describes precipitation in all its shapes and sizes. Here you get the idea of different air masses meeting along fronts like opposing armies.

The Weather Celebrities

      Weather is a very popular subject when there are big storms brewing