2Water is one of the more essential components needed to sustain life on Earth. All water on the planet in all its states--frozen, liquid, and gaseous--make up the hydrosphere. Readers of this captivating volume will learn that liquid water not only exists on the surface of the earth but also in reservoirs underground. They'll also learn that frozen water exists as glaciers, ice caps, and icebergs, making up a special subcategory of the hydrosphere called the cryosphere, and that water can even be found in the atmosphere in the form of water vapor. Key STEM concepts are reinforced with eye-catching graphic elements and accessible text.