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Introduction

      Weather is a big part of life. It is part of life in the sense that weather is something that everyone experiences more or less directly every day. And weather’s extremes of storm and heat are something that most people have to put up with at one time or another.

      But weather is part of life in another, bigger sense. It is part of life in the same way the air that you and I breathe is part of it. Often weather gets talked about as something that interferes with travel plans or interrupts a picnic, but that is not the point. Without weather, there is no picnic. No food, no forest, no flowing fresh water.

      What’s going on up there when the wind blows, when the clouds roll in, when the rain falls and the lightning flashes? To wonder about these things is to share some thoughts with the first people who poked their heads out of a cave and looked up into the dark sky of a violent storm. It is part of being human. This wondering about the weather came long before there was reading and writing and science, and long before there were reasonable explanations for these things. Some of the old explanations, you wouldn’t believe. The wind, the clouds, the rain, and the lightning make a lot more sense to the likes of you and me than they used to, but when all is said and done, you have to admit, still they are wonderful!

About This Book

      The reasonable weather explanations that separate you and me from the folks poking out of the cave are part of the modern knowledge specialty of meteorology, which is the five-dollar word for the science of weather and climate. That’s what this book is all about. Weather scientists know the answers now to the basic questions about the changes that take place in the sky and plenty more.

Already you know more than you probably think you do about the weather. Phrases like “low-pressure system” and “high-pressure ridge” have become familiar, even if not so well understood. And images from space satellites of enormous arms and blotches of cloudiness slowly swirling over the surface of Earth appear on television screens and on our smartphones as familiar as the faces of friends. Already you are ahead of people who wondered about the weather some 60 years ago before the satellites went into orbit and made the great size of storms so obvious.

      So even before you tackle the details of the comings and goings in the air over your head, some congratulations are in order. In most times past, when people wondered about the weather, they were scared to death. They were frightened by the storms, and when they asked questions about them, they were frightened by the answers they got. If I told you it was the magic of the witch doctor, or the fact that the gods are angry, now you would laugh at me. You and I have come a long way, baby.

      There is no right way to read this book, and no wrong way to read it either. You can read it straight through from the first page to the last, but you don’t need to. You don’t need to read Chapter 1, for example, to get a grip on the subjects covered in Chapter 2. Browse through it or start anywhere you like. If there’s something about how weather happens that’s been bugging you, just jump in and check it out. (Why the sky is blue is explained in Chapter 15, for example.) Weather For Dummies is your ready reference on the subject.

Foolish Assumptions

      To write this book, I had to make some assumptions about you. I think you are somebody who enjoys watching the changes that take place in the sky from day to day, or month to month. You take some satisfaction in knowing what’s behind these changes. You like to know the meaning of the words you hear or read in the daily weather reports simply because you like to know the meaning of the words you hear. And from time to time, you have some questions about how the weather works.

      You are a consumer of weather information. You are not a mathematician. You are not a weather scientist or forecaster. You have a natural curiosity about the weather, and a healthy respect for it. But you are not crazy-in-love-with-it like a storm chaser who runs out the door with a video camera at the first word of severe thunderstorms nearby. You are not a “weather geek,” someone who really wonders about the weather a lot and who devours every bit of information they can find on the subject. Although maybe you are a weather geek and you just don’t want to admit it yet. If this is the case, your secret is safe with me!

Icons Used in This Book

      In the pages of Weather For Dummies are a set of symbols that alert you to certain kinds of information. They help you sort through the wide variety of facts and details and put them in your own order. Here’s what these symbols mean.

      

This icon lets you know about a concept, or big idea, that is not just a detail about the weather, but is a whole train of thought on a subject. Big ideas are not complicated. In fact, they are simple. They’re important, or big, and worth checking out, because they help explain a lot of details.

      

Some words are just weather words. There are a whole lot of special weather words that scientists use all the time when talking to each other, and this book avoids most of them. The ones you find at this symbol are included because they are helpful or interesting.

      

Some kinds of information are valuable because they make complicated easy or they help cut through a lot of detail to a useful idea. That’s the kind of thing this symbol points out, an idea that makes things a little quicker or easier.

      

A lot of details are useful only to a specific subject, but some things are valuable to keep in mind because they help explain a variety of things. That kind of good-to-remember information is what this symbol identifies.

      

Some weather situations are so dangerous that they should be avoided always. Most of the dangers are pretty obvious, but not all of them. This symbol alerts you to extreme weather conditions where dangers are clear and present. It also points you to tips about what to do if you are hurt by the weather.

      

Don’t be alarmed by this nerdy-looking guy. The technical stuff included in this book is not really the heavy-duty number-crunching kind of thing that weather scientists do once in a while. This symbol alerts you to stuff that’s just a little more technical than the rest.

A Note about Measurements

Because this book is published in the United States, I have adhered fairly closely to the use of imperial measures of temperature and length (degrees Fahrenheit and inches) rather than their metric counterparts (degrees Celsius and centimeters), which are used more commonly by the rest of the world. Chapter 2 has a Fahrenheit to Celsius conversion chart that may be helpful, and Chapter 4, which discusses the amounts of rainfall and other precipitation, includes a chart that converts inches to centimeters and millimeters.

Beyond the Book

      In