15.1 Worksheet
1.
In chemistry, the word “salt” doesn’t just refer to the thing we sprinkle on our food (NaCl).
What kinds of things are included when we say “salt”?
Any metal mixed with a nonmetal. There are other salts in the ocean.
2.
Salinity = the total amount of dissolved solids in water. What is the average salinity of ocean
water?
35 o/oo (parts per thousand) OR 3.5% (percent or parts per hundred)
3.
What is the most common “salt” contained in sea water?
NaCl (Sodium Chloride or table salt)
4.
What is the most common source of dissolved solids in sea water? What is the 2nd most
common source?
1. Weathering of rocks from land 2.volcanoes
5. The salinity of the ocean is calculated with a simple ratio:
Amount of dissolved solids = salinity
Amount of fresh water
The ocean is very well-mixed and the processes that add dissolved solids remain relatively
constant. Therefore, it’s not likely that salinity would change by adding or taking away dissolved
solids. This leaves only one alternative: salinity can be changed be adding or taking away
amounts of fresh water. Below, make a list of the processes that will:
ADD fresh water, DECREASING salinity
REMOVE fresh water, INCREASING salinity
Precipitation
Runoff from land
Melting icebergs
Sea ice melting
Evaporation
Freezing
Sea ice formation
6.
The ocean’s surface waters will change temperature with the amount of solar radiation
(sunlight received). As you learned at the beginning of the year, the amount of sunlight the
Earth receives varies with latitude. Use the data from figure 3 to fill out the table below and
make a summary statement
Latitude
60 North
Approx. Surface Temp.
30 North
10 C
0C
0 (Equator)
25 C
30 South
10 C
60 South
0C
7.
Summarize the relationship between
temperature and latitude:
As latitude decreases
(closer to the equator),
temperature increases.
The sun can’t reach very far into the ocean. Because of this, the temperature begins to quickly
drop as you increase depth in the ocean. This rapid change in temperature with depth is called
the thermocline. Why is there no thermocline in the high latitude diagram below?
Because the poles receive
very little direct sunlight
throughout the year. Not
enough to even warm
surface.
8.
Density = mass/volume (or how much stuff is in a given space). Density of sea water will change
based upon two factors:
a. Temperature. (Liquid) water expands when heated. Based upon this info, fill in the
blank below
Temperature increase = density ___decreases___
b.
Salinity. As you dissolve more solids into the same volume of water, you are putting
more “stuff” in the same space. Based upon this info, fill in the blank below
Salinity increase = density __increase__
9.
Based changes in salinity and temperature, the density of sea water will vary at different
latitudes and depths. This change in density with depth is called the pycnocline. What is the
single most important factor affecting density in this graph? ______Temperature.
As
more sunlight/heat is received, water expands. This makes
surface water at low latitudes less dense. ___________________
10. Why is density in sea water such an important factor?
It will determine whether water will float or sink above other layers of
water. **Water of different density doesn’t mix easily**
11. Summarize the key differences between the following ocean layers
a. Surface zone/Mixed
Zone
 2% of total water in ocean
 Extends down from surface to 300-450m
 Roughly same temp: WARM
b. Transition zone
 Between surface & deep
 18% of total water in ocean
 Temperature begins to drop here
 Density begins to increase
 Where the thermocline and pycnocline exist
c. Deep zone




80% of ocean water
Lowest layer
COLD and DENSE
No sunlight
12. The diagram below shows a cross-section of the world’s oceans and how they vary by latitude.
Why do we ONLY see deep zone water at high latitudes?
Because there is no warming of water @ surface. Low amounts of
sunlight at high lats.
Why do we see a large transition zone between 40N and 40S?
Surface waters are heated and deep water is not. Transition zone
is in the middle of these layers that don’t want to mix together.