57 The Water Cycle-Low

The Water Cycle Written by Robert N. Knight

《水循环》罗伯特·N。 骑士

Introduction Water covers three-fourths of Earth's surface. This is why Earth is called the "water planet." Each year, more and more people live on Earth. They use more and more water. They cause dirt to get into Earth's water. For all these reasons, clean water is more precious. This book will teach you about how Earth's water moves and changes. It will also teach you how we use water and how we can conserve it.

水覆盖了地球表面的四分之三。 这就是为什么地球被称为“水行星”。 每年，越来越多的人生活在地球上。 他们使用越来越多的水。 它们会导致泥土进入地球的水中。 基于这些理由，干净的水更加珍贵。 这本书将教你地球上的水是如何移动和变化的。 它还将教你如何使用水，以及如何节约用水。

The world's oceans hold most of Earth's water. However, this water is salt water. Salt water is not good for drinking or watering plants. A very small amount of Earth's water is not salt water. Fresh water is in lakes, rivers, and streams. Some of it is found below the ground and high in mountains, too. But most fresh water is found in the form of ice around the North and South Poles.

世界上的海洋拥有地球上大部分的水。 然而，这水是盐水。 盐水不适合饮用或浇灌植物。 地球上有非常少量的水不是盐水。 淡水在湖泊、河流和小溪中。 其中一些在地下和高山中也有。 但大部分淡水都是以冰的形式存在于南极和北极周围。

The Movement of Water Everything on Earth is matter. The three states of matter are solid, liquid, and gas. Earth's water is found in all three of these states. Solid water is ice Water that is a gas is water vapor. You cannot see water vapor. Liquid water is the water you drink and see fall as rain. Earth's water moves all around Earth. As it moves, it changes states. This movement is called the water cycle.

地球上的一切都是物质。 物质的三种状态是固体、液体和气体。 地球上的水都存在于这三种状态中。 固态的水是冰，气态的水是水蒸气。 你看不到水蒸气。 液态水是你喝的水，你看到它以雨的形式落下。 地球上的水在地球周围流动。 当它移动时，它改变了状态。 这种运动被称为水循环。

The first step in the water cycle happens when the Sun shines on water. This sunlight is energy. Some of this energy passes to the tiny particles that make up water. The particles get more and more energy from the sunlight. They move faster and faster. When they move fast enough, they leave the water and move into the air above the water. This process is called evaporation. Evaporation happens when liquid water changes to water vapor.

水循环的第一步发生在太阳照射在水面上的时候。 这种阳光就是能量。其中一些能量传递给了构成水的微小颗粒。 粒子从阳光中获得越来越多的能量。 他们移动得越来越快。 当它们移动得足够快时，就会离开水面，飞到水面上方的空中。 这个过程叫做蒸发。 当液态水变成水蒸气时，蒸发就发生了。

Warm air near Earth's surface rises. As it rises, it cools. The tiny water particles in the cool air slow down and get closer together. They begin to gather on tiny bits of dust that are floating in the air. As water particles collect on the dust, they form water droplets. This process is condensation It's the next step in the water cycle. When millions of these water droplets come together, they form clouds. The more water droplets that come together, the thicker the clouds become. When clouds become very, very thick, they can form storm clouds.

地球表面附近的热空气上升。 当它上升时，它就会冷却。冷空气中的微小水粒子会减速并靠得更近。 它们开始聚集在空气中漂浮的微小尘埃上。 当水粒子聚集在灰尘上时，就形成了水滴。 这个过程是冷凝，这是水循环的下一步。 当数百万个这样的水滴聚集在一起时，它们就形成了云。 聚在一起的水滴越多，云就越厚。 当云变得非常非常厚时，就会形成风暴云。