5 Questions
What percentage of the Earth's surface is covered in water?
Two-thirds
What process occurs when the sun heats the water in the sea, changing it into a gas?
Evaporation
What type of minerals are dissolved from rocks and enter the water?
Sodium and chloride
What is the main salt in seawater?
Sodium chloride
What is the term for the process by which water falls from the clouds in the sky?
Precipitation
Study Notes
Water Coverage on Earth
- 2/3 of the Earth's surface is covered in water, with 97% of it being salty seawater.
- Only 3% of the Earth's water is fresh, found in rivers, lakes, and streams.
The Water Cycle
- Water moves around the planet in a cycle powered by the sun.
- The cycle involves: evaporation, condensation, precipitation, and runoff.
Evaporation
- The sun heats seawater, turning it into water vapor.
- Water vapor rises into the air through evaporation.
Condensation
- Water vapor in the air turns back into liquid water, forming clouds.
- This process is called condensation.
Precipitation
- Water from clouds falls to the ground as rain, sleet, hail, or snow.
- This process is called precipitation.
Rainwater and Mineral Salts
- Rainwater contains small amounts of carbon dioxide and sulphur dioxide, making it slightly acidic.
- The acidic rain absorbs small amounts of mineral salts, including sodium and chloride.
- These mineral salts are dissolved from rocks and enter the water.
The Salinity of Seawater
- The main salt in seawater is sodium chloride.
- Rainwater flowing into rivers and streams carries dissolved salts, making seawater salty.
Learn about the water cycle and how freshwater plays a crucial role in making seawater salty. Discover the process of evaporation and condensation that makes the sea salty.
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