History, Composition, and
Water Cycle

How did the oceans form?
• Volcanic gases formed the Earth’s atmosphere. When Earth cooled, the water vapor in the atmosphere condensed and fell as rain. The rain collected on the surface to form the oceans.

How did the oceans form?

Composition of Ocean Water
• Salinity: the amount of salt dissolved in ocean water
– 1kg of ocean water contains 35g of salt.
– Ocean contains many different kinds of salts.
Salt comes from dissolved minerals in rivers and streams.

What effects salinity?
• Climate
– Hot climates cause evaporation which makes water saltier (ex. Red Sea)
– Saltier near the poles (salt is left behind when water freezes)
• Water movement
– Slow moving areas of water have higher
Ex. Gulf of salinity
Mexico
• Density
– Water at the surface is less salty than water at the bottom of the ocean

Temperature Zones
• Temperatures vary with location
• Temperature is warmer near the surface and cooler near the bottom
**Temperature drops and pressure increases as you go deeper underwater!!
Cold Water
Warm Water
Cold Water
Warm Water
Cold Water

The Ocean & the Water Cycle
• Water Cycle = the continuous movement of water from the ocean to the atmosphere to the land and back to the ocean.