Chapter 13; Section 1

Earth’s Oceans

Why does coastal water in places with hotter, drier climates typically have a higher salinity than coastal water in places with cooler, more humid climates?

Bellringer

Why does coastal water in places with hotter, drier climates typically have a higher salinity than coastal water in places with cooler, more humid climates?

Coastal water in places with hotter, drier climates has a higher salinity because less fresh water flows into the ocean in drier areas, and because heat increases the evaporation rate.

Bellringer

Objectives• Describe the history of Earth’s

oceans.

• Identify the properties of ocean water.

• Describe the interactions between the ocean and the atmosphere

Earth’s Oceans

• About 4.5 billion years ago, there were no oceans.

• Sometime before 4 billion years ago, water vapor in the atmosphere condensed and fell as rain.

• The rain filled the deeper levels of Earth’s surface and the first oceans began to form.

1. The history of Earth’s oceans

1. The history of Earth’s oceans

2. The properties of ocean water Dissolved Gases Nitrogen, oxygen,

and carbon dioxide are the main gases dissolved in ocean water.

Solids Sodium chloride, or table salt, is the most abundant dissolved solid in the ocean. Other solids are also found in ocean water.

2. The properties of ocean water• Salinity is a measure of the amount

of dissolved solids in a given amount of liquid.

• Changes in Salinity Climate and water movement affect salinity. Costal water in cool, humid places has a low salinity. Slow-moving bodies of water have higher salinity than other parts of the ocean do.

2. The properties of ocean waterCompare Hudson Bay & an Egyptian

CityUse page 377 to find salinity levels

2. The properties of ocean water Temperature Zones The

temperature of ocean water decreases as depth increases.

2. The properties of ocean water• Surface Temperature Changes

Surface-zone temperatures vary with latitude and the time of year.

• Surface temperatures range from 1ºC near the poles to about 24 ºC near the equator.

• The surface zone is heated more in the summer.

3. The interactions between the ocean and the atmosphere

• The water cycle is the continuous movement of water from the ocean to the atmosphere to the land and back to the ocean.

• The ocean is an important part of the water cycle because nearly all of Earth’s water is in the ocean.

3. The interactions between the ocean and the atmosphere

3. The interactions between the ocean and the atmosphere

• The ocean regulates atmospheric temperatures.

• A Thermal Exchange The ocean absorbs and releases thermal energy much more slowly than dry land does.

• The circulation of warm water causes some coastal lands to have warmer climates than they would have with the currents.

Objectives• Describe the history of Earth’s

oceans.

• Identify the properties of ocean water.

• Describe the interactions between the ocean and the atmosphere

Earth’s Oceans