Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 17

While plants and animals have life cycles, water has a life cycle of its own. Following the rule of “what goes up must come down,” the life cycle of water, commonly referred to as the hydrologic cycle, describes the way water travels around the globe from ocean to air to land and back again to the ocean (see Figure 1-2).

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FIGURE 1-2: The hydrologic (water) cycle.

Water is a wonderous element which can take on three different states of being. It can exist in a solid state (ice), a liquid form (water), or a gaseous state (steam), in which it evaporates and becomes vapor (humidity). When humid air is cooled, the water forms droplets and falls back to the earth as precipitation — in either liquid form (as rain) or in solid form (as snow or hail).