Our water polo Some people say that our earth should be called water polo. This makes sense, because the planet we live in has water, and 7 1% of its surface area is occupied by water. In the eyes of astronauts, the earth is a blue ball, which is very splendid and unique in the solar system family. The earth's water resources are huge, totaling 65.438+38.6 million cubic kilometers. Among them, 96.5% are in the ocean; 1.76% is solid in glacier, frozen soil and snow; 1.7% is underground; The rest are scattered in lakes, rivers, atmosphere and organisms. So it can be said that from the sky to the underground, from the land to the ocean, there is a world of water everywhere.
Earth-shattering water cycle The water in the world is a connected whole. Under the irradiation of sunlight, seawater is constantly evaporating and water vapor diffuses over the ocean; Part of the water vapor is carried to the land by the airflow. When it is cold, it condenses into tiny water droplets and becomes clouds. When it falls to the ground, it is rain or snow. After the rain, snow and water fall to the ground, some of them flow into potholes, some seep into the ground, some flow into gullies, merge into rivers and rush to the ocean. Countless water drops travel around the world all the time. The water cycle ensures the supply of fresh water for human beings. Knowing the circulation of water can explain: where is the hometown of clouds? Why do rivers always flow day and night? Why have so many rivers and rivers flowed into the ocean for thousands of years, but the ocean has not flooded?
Where can fresh water enter the water on the earth? Although the number is huge, it is pitiful that people can directly use it for production and life. First of all, seawater is salty and bitter, so it can't be drunk, irrigated or used for industry. Secondly, fresh water only accounts for about 2.6% of the total water, and most of it (99%) is frozen in the north-south layer far away from human beings and frozen soil, so it can't be used. Less than 65,438+0% of fresh water is scattered in lakes, rivers and underground. Compared with all the water bodies in the world, the quantity of fresh water is actually nine Niu Yi hairs.