What Is Weather?

When we use the term weather, we are referring to conditions in the atmosphere at some specific time and place, whether it is right now, an hour ago, or sometime next week. Weather refers to the temperature, humidity, and windiness, and if it is fair or there is precipitation. It also refers to whether an area is experiencing severe storms, such as a thunderstorm, tornado, hurricane, or snow storm, or is in a time of exceptional dryness. Weather refers to the various aspects featured on these two pages, and much more! Examine the four maps on this page and figure out what the weather was like on April 27, 2011 where you live.

Weather affects all of our lives, from deciding what clothes to wear, what week to plant crops, or how soon to take shelter from some type of severe weather. In this chapter, we explore the fundamental processes that control weather and then examine the main types of weather phenomena, including rain and snowstorms, freezing rain, thunderstorms, hail, lightning, hurricanes, and, of course, tornadoes. Along the way, we explain features you can observe, like the types of clouds, to understand and predict the weather around you.