Oceanography
The ocean is not just a giant, still puddle of salty water. It is constantly moving, swirling, and flowing in massive global rivers. Join Bill Nye the Science Guy as we dive into the deep to discover the invisible forces that push quadrillions of tonnes of water around our planet.
Rivers of Water Flowing Through Water!
It stays behind in the ocean! When ocean water turns into vapour and floats up to form clouds, the heavy salt is left behind. This makes the remaining surface water even saltier and heavier!
Rainwater constantly rinses their minerals downhill! As water flows from the mountains to the sea, it carries tiny amounts of salt with it. Because the ocean has no outlet, that salt has been building up there for over a billion years.
Put Your Instincts to the Test
Think about what you already know about water and weather. Pick an answer for each question, then see if your instincts were right.
The glass of water! Water holds onto heat much better than air does. This is incredibly important because it means the massive oceans help regulate the temperature of the entire planet.
They expand, get lighter, and rise! Heat energy makes molecules move faster and push farther apart. Because they take up more space, the water becomes less dense and floats to the surface.
The rotation of the Earth! If our planet did not spin, the water would just move in straight lines from the equator to the poles. The spinning Earth curves the currents, an effect scientists call the Coriolis Effect.
Understanding the Science
Tap each card to uncover the forces and phenomena that keep the global ocean in constant motion.
Key Concepts
Ocean Currents
Tap to learn moreMassive rivers of water flowing within the ocean itself, moving incredible amounts of water, heat, and nutrients all over the world.
Thermohaline
Tap to learn moreA scientific word made of two parts where "thermo" means heat and "haline" means salt. Together, heat and salt drive the deep ocean currents.
Evaporation
Tap to learn moreThe process where the sun heats ocean water and turns it into vapour, leaving the heavy salt behind in the sea.
Density
Tap to learn moreThe reason why things sink or float. Salty or cold water is very dense and sinks, while fresh or warm water is less dense and rises to the surface.
Gulf Stream
Tap to learn moreA massive warm current in the Atlantic Ocean that carries tropical heat all the way up to Europe, keeping the climate surprisingly mild.
Coriolis Effect
Tap to learn moreBecause the Earth is constantly spinning, ocean currents are pushed into massive circular patterns instead of flowing in straight lines.
Heat Capacity
Tap to learn moreThe ability of water to hold onto heat much better than air, which prevents our planet from completely freezing at night.
Plankton
Tap to learn moreTiny floating plants and animals that cannot swim against the currents, completely depending on the flowing water to move them around.
Try It: The Thermohaline Chamber
You control the climate! Use the sliders to apply extreme heat to the equator or freezing cold to the poles.
The Mission: Adjust the temperatures to see how heat expands the water to make it rise, while freezing cold makes it dense enough to sink, driving a massive global current!
Apply Your Knowledge
Let us see if you can connect these physical forces to their effects on the global ocean.
Match the Concepts
Click a concept to select it, then click the matching description to place it.
Real-World Challenge
Imagine a massive glacier suddenly melts due to an unusually hot summer, dumping millions of litres of freezing cold, entirely fresh water into the salty ocean. Based on what you know about density, would this freezing fresh water sink straight to the bottom or float on the top of the salty seawater?
What Has Changed Since This Episode Aired
This episode aired in 1994. While the core physics of oceanography remain completely accurate, the tools we use to study the sea have vastly improved.
Updated: While simple drift cards are still occasionally used, today oceanographers rely heavily on fleets of autonomous, satellite-linked robotic floats. These advanced robots can dive thousands of metres underwater to measure temperature and salt levels, then bob back up to the surface to beam their data directly to scientists!
Updated: Scientists are now monitoring the Gulf Stream very closely using advanced computers. They are concerned that climate change and melting polar ice caps could dump too much fresh water into the ocean, which might disrupt the delicate salt balance and slow the mighty Gulf Stream down!
Test Your Understanding
Answer these questions and get instant feedback. How many can you get right?
Results
Your score:
Reflection
Think about the weather where you live. Do you live near the coast, or far inland? Based on what you learned about how water holds heat, how do you think the ocean affects your local summer and winter temperatures?
Episode Discussion
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