How Seawater Becomes Salty

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.