Ask Me EverythingW

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How does w&ter shape Earth?

FAST FACTS

\Water is the defining feature of our planet. There may be ice and water vapor on other planets in the solar system, but only Earth definitely has oceans, rivers, and lakes of liquid water, covering two thirds of the planet. The other one third—the land —owes most of its character to water erosion and the spread of plants, which could not exist without water. Indeed,

without water, there would be no life.

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01: Water is a Chemical compound of two gases, hydrogen and oxygen. Two atoms of hydrogen are bonded to one atom of oxygen to make each molecule of water: H₂0.

02: The three atoms in each water molecule are held together by electrostatic charges that make them form a flattened triangle.

03: Each molecule has a negative charge on the oxygen atom and a positive charge on each hydrogen atom, so it behaves like a tiny triangular magnet.

04: This makes the molecules stick together loosely as a liąuid. If they are heated, the added energy makes them burst apart to form a gas— water vapor.

On the other hand, if water is cooled to below 32°F (0°C), the molecules lock together in the regular, rigid crystal structure of solid ice.

4 Some underground water \ f reservoirs were formed long ago in regions that are now deserts. Sealed in by morę rock, the water may be 20.00U years old. One of these desert reservoirs lies beneath the eastern Sahara, and contains around 36,000 miles³ \    (150,000 km³) of water! J

Weird properties of water

4 Water is strange stuff. For one thing, it is very heavy, which is odd considering that it is madę of two gases—and that one of these gases, hydrogen, is the lightest substance in the universe!

4Uniquely, water expands as it freezes. So ice is less dense than water, and this is why it floats. Just think—if water behaved like any other substance, lakes would not freeze over in the winter. They would freeze under!

4 Water molecules stick together so strongly at the water surface that they form an elastic film called surface tension. This is strong enough for smali animals to walk on.

A The forces that make water W molecules cling together also make them cling to atoms of other substances such as salt, pulling them apart and dissoMng them. In fact, water can dissolve morę substances than any other liguid.

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Tell me morę: water cycle

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Most of the water on Earth probably erupted from massive volcanoes some four billion years ago, collecting as water vapor in the atmosphere. As the planet cooled, the vapor turned to rain that poured down for millions of years to create the oceans!

Ali life on land relies on the water cycle, which delivers water from the oceans to the continents and back again.

02: Here, it cools and condenses into the tiny water droplets that form clouds.

01: The heat of the Sun turns salty ocean water to pure water vapor, which rises into the air.