As the wind begins to pick up and dark clouds gather overhead, a weather-curious child may wonder: What natural systems are causing this storm to form? This book will explain how fronts cause storms, and how air masses are an important element of fronts--and all weather on Earth! Specifically, this book features accessible text that describes continental and maritime air masses, cold fronts, warm fronts, the jet stream, El Nino, La Nina, and how fronts and air masses allow professionals to predict the weather. Colorful images and intriguing fact boxes make this title one that will be valuable to both aspiring meteorologists and students simply interested in understanding more about the weather forecasts that affect their everyday lives.