Ocean Currents Lab 2

📖

Part 1: Surface Ocean Currents

Read carefully — answer questions on the next page

Key Vocabulary

Ocean Current

A large, directed movement of ocean water driven by wind, temperature, or salinity

Gyre

A large system of circular ocean currents driven by global wind patterns

Thermohaline Circulation

Deep ocean circulation driven by differences in water density (temperature + salinity)

Gulf Stream

A powerful warm ocean current flowing northward along the eastern coast of North America

Salinity

The amount of dissolved salts in ocean water, measured in parts per thousand (ppt)

Density

Mass per unit volume — cold, salty water is more dense and sinks

Upwelling

The rising of cold, nutrient-rich water from deeper layers to the surface

ESRT

Earth Science Reference Tables — NYS reference resource for lab and exam use

🌊 What Are Ocean Currents?

Ocean currents are large-scale flows of seawater that move in predictable patterns around Earth's ocean basins. They can be thought of as "rivers within the ocean." There are two major types: surface currents, driven primarily by global wind belts, and deep ocean currents, driven by differences in water density.

Surface currents affect roughly the top 100 meters of the ocean and are set in motion by Earth's prevailing wind patterns. Because Earth rotates, these currents do not flow in straight lines — they are deflected by the Coriolis effect. In the Northern Hemisphere, currents curve to the right; in the Southern Hemisphere, they curve to the left. This creates large circular patterns called gyres.

🔑 Key Rule: Northern Hemisphere gyres rotate clockwise. Southern Hemisphere gyres rotate counterclockwise.

🗺️ ESRT — Surface Ocean Currents Model

The image below is from the NYS Earth & Space Sciences Reference Tables (ESRT). Use it to identify major warm and cold currents worldwide.

Notice the key at the bottom right: dashed arrows = warm currents and solid arrows = cold currents. Warm currents generally flow away from the equator; cold currents flow toward it.

🌡️ Warm vs. Cold Currents

☀️ Warm Currents

• Flow away from the equator
• Found on the eastern sides of continents in the Northern Hemisphere
• Moderate (warm) the climates of nearby land
• Example: Gulf Stream (warms NW Europe)

🧊 Cold Currents
• Flow toward the equator
• Found on the western sides of continents in the Northern Hemisphere
• Cool and dry the climates of nearby coasts
• Example: California Current (cools US West Coast)

🔄 Thermohaline Circulation — The Ocean Conveyor Belt

While surface currents are wind-driven, the deep ocean is set in motion by density differences in water. Cold water is denser than warm water, and salty water is denser than fresh water. When surface water in polar regions becomes very cold and salty (as ice forms, leaving salt behind), it sinks to the deep ocean floor and flows slowly toward the equator.

This global system is sometimes called the "ocean conveyor belt" or thermohaline circulation. It plays a critical role in transporting heat around Earth and regulating global climate. If this system slows — for example, from freshwater input due to melting glaciers — it can cause dramatic climate changes.

⚠️ Climate Connection: Scientists are concerned that as the Greenland ice sheet melts due to global warming, the influx of fresh water into the North Atlantic is lowering the region's salinity and density — potentially slowing or disrupting thermohaline circulation. This could paradoxically cause cooling in Western Europe even as global temperatures rise.

✏️

Part 2: Reading Comprehension Questions

Answer each question based on the reading. Complete all blanks.

Complete Each Statement

1 Ocean currents that flow from the tropics toward the poles are classified as currents.

2 The Coriolis effect causes currents in the Northern Hemisphere to curve to the .

3 Large circular systems of ocean currents are called .

4 The Gulf Stream is a current that flows along the coast of the United States.

5 Thermohaline circulation is driven by differences in water , which is affected by both temperature and salinity.

6 Cold, salty water because it is more dense than warm, less-salty water.

7 In the Southern Hemisphere, ocean gyres rotate in a direction.

8 The California Current, found along the western coast of North America, is classified as a current.

Short Answer

9

Explain why melting glaciers in Greenland could disrupt thermohaline circulation. Use the words salinity, density, and sinking in your answer.

10

Using the ESRT Surface Ocean Currents Model, name ONE warm current and ONE cold current found in the Pacific Ocean.

🦆

Part 3: Case Study — Rubber Ducks & the Pacific

Read the passage, then answer questions using word banks provided

📰 Case Study Reading

Complete Each Statement About the Case Study

1 The container ship in this case study was named the .

2 The accident released over plastic bath toys into the ocean.

3 The Great Pacific Garbage Patch (GPGP) is approximately square kilometers in area.

4 Garbage patches form inside ocean where water conditions are calm.

5 Scientists study the GPGP to determine the of the plastic in order to reduce pollution.

🔀 Sentence Builders

Click the words in the correct order to build each sentence. The green word is already placed for you.

Sentence 1

Use all the words below to complete the sentence about ocean currents and trash.

trap ocean floating trash gyres

Large

✅ Correct! Large ocean gyres trap floating trash.

Sentence 2

Build a sentence about the Gulf Stream and climate.

climate Gulf Stream Western Europe warms

The

✅ Correct! The Gulf Stream warms Western Europe's climate.

Sentence 3

Build a sentence about thermohaline circulation.

sinks because it is dense water cold salty

Very

✅ Correct! Very cold salty water sinks because it is dense.

Sentence 4

Build a sentence about the Coriolis effect.

curve right Northern Hemisphere currents

In the

✅ Correct! In the Northern Hemisphere, currents curve right.

📊

Part 4: Data Analysis

Analyze data tables and answer questions about ocean currents

Coastal City Temperature Comparison

Two cities at the same latitude (45°N) have very different climates due to nearby ocean currents. Study the table below.

City	Latitude	Nearby Current	Current Type	Jan Avg Temp	July Avg Temp
Portland, Oregon (USA)	45°N	California Current	Cold	41°F (5°C)	68°F (20°C)
Bordeaux, France	45°N	North Atlantic / Gulf Stream	Warm	46°F (8°C)	75°F (24°C)

1

Which city is warmer in winter? Explain why using ocean current type.

2

Both cities are at 45°N latitude. What does this tell you about the role of ocean currents vs. latitude in determining climate?

Ocean Water Density Comparison

Use the data below to answer questions about thermohaline circulation.

Water Sample	Temperature	Salinity (ppt)	Relative Density
A – Tropical surface water	28°C	34	Lowest
B – Mid-latitude surface	16°C	35	Medium
C – North Atlantic deep water	2°C	35	Highest
D – Greenland meltwater	0°C	5 (fresh)	Low

3

Which water sample (A, B, C, or D) would sink to form deep ocean currents? Explain using temperature AND salinity.

4

Sample D represents water from melting Greenland glaciers. How would a large influx of Sample D into the North Atlantic affect thermohaline circulation? Explain your reasoning.

🎯

Part 5: Regents-Style Quiz

10 questions selected from a 20-question bank • 1 point each

🏆

Lab Complete — Final Summary

Your work has been recorded

—

Quiz Score

🖨️

Save or Print Your Lab

Print to PDF to save a copy of your completed lab for your teacher.

📋 Completed Lab Summary

Student: — | Period: — | Date: —

Part 2 — Reading Questions: Completed

Part 3 — Case Study: Completed

Part 4 — Data Analysis: Completed

Part 5 — Quiz: —

Surface Currents · Thermohaline Circulation · Real-World Case Study

📋 Learning Objectives