This document summarizes key aspects of Earth's hydrosphere including ocean chemistry, currents, waves, and tides. It explains that oceans contain 3.5% salt by mass and salinity varies due to evaporation. Ocean currents are large bodies of moving water that flow in predictable patterns and can affect climate. Waves are caused by wind and deep water is less affected than surface water. Tides are the daily rise and fall of sea levels caused by the gravitational pull of the Moon and Sun, with most effect from the Moon, resulting in two high and low tides every 24 hours.

1. Earth’s Hydrosphere – Salt Water g. Trench
Chapter 13 Chapter 14
I. Ocean chemistry I. Ocean currents
a. For every 1000 grams of ocean water, 35 of those grams are a. An ocean current is a “river” of moving water with the
salt (3.5% of mass). This means that 100 pounds of ocean ocean. An example would be the Atlantic Gulf Stream.
water would contain 3.5 pounds of salt! The water in the current has the same properties and
b. Salinity refers to the amount of dissolved salts in H2O. does not mix much with the rest of the ocean.
c. Most of the salt in the ocean is NaCl. b. All ocean currents flow in predicable patterns.
d. Variations in salinity are due to evaporation rates. More c. Surface currents, like waves, are driven and
evaporation means higher salt content because water can determined by wind and the Coriolis effect (be able to
evaporate but salt cannot. explain the Coriolis effect).
e. Why is the ocean salty? Water that moves across the earth d. Ocean currents can affect climate by warming or
dissolves the salt and carries it to the ocean. When water cooling the air above the current. Example – England is
evaporates from the ocean, it leaves the salt behind. warmer that it should be based on its latitude because
f. As depth changes in the ocean the environment changes. of the Gulf Stream current coming from the southern
i. Less light is available as you go deeper. Life has to USA.
adapt. II. Wave formation
ii. As you go deeper, the temperature drops. Surface a. Caused by wind blowing over long distances. Also
water is usually warmer than deep water. affected by how long the wind has been blowing.
iii. Pressure of the water increases with depth because b. Deep water is not affected by wave motion as much as
more water is on top pressing down. the surface. See the diagram on page 430.
iv. Salty water is more dense than fresh water. That
means that salty water wants to sink below fresh
III. Tides are the daily rise and fall of sea level along a
water. coastline.
v. Cold water is more dense than warm water. That a. Tides are caused by the gravitational pull of the moon
means that cold water wants to sink below warm water. and sun on the earth. Most of the effect is caused by
g. These properties cause water to want to move around. This the moon.
affects currents. i. There are two high tides and two low tides
every 24 hours.
II. New technology has been developed to explore the ocean floor.
ii. This means the tide goes from high to low in
Know the following and how we use that technology: about 6 hours.
a. SCUBA
b. Sonar
c. Submersibles
d. Satellites
III. Feature of the ocean floor:
a. Continental shelf
b. Continental slope
c. Continental rise
d. Abyssal Plain
e. Mid-ocean ridge
f. Seamount