Ocean currents influence weather and climate
If you look at a world map, you can see that Earth’s 5 oceans are vast. In fact, they cover more than 70% of Earth. But what makes oceans different from freshwater is that they contain salt and minerals.
This is because heat from the sun evaporates water. When water evaporates, salt remains in the ocean. The water vapor rises into the sky, cools and forms clouds. Then, it falls down as rain again.
Ocean currents are like giant conveyor belts flowing through the oceans moving huge amounts of water all the time. While wind drives surface ocean currents from the coriolis effect, temperature and salt gradients mostly influences deep ocean currents.
Let’s examine the types and causes of ocean currents in the world. Why are ocean currents important? And what are the names of some of their names?
Warm currents vs cold currents
The wind and sun makes ocean currents move. At the equator, the sun is strongest heating water the most there. When water heats, water molecules vibrate faster and eventually move farther apart.
From the equator, hot water pushes outward to south and north pole. At the same time, cold water from the north and south poles collide with this warm water. Because Earth spins on its axis, water flows in a circular pattern. For example, oceans in the northern hemisphere move mostly clockwise. But in the southern hemisphere, ocean currents move mostly counter-clockwise.
For example, the Gulf stream current pushes warm air to Europe. It flows around the Atlantic ocean like a clock. Because of the Gulf stream, this is why parts of Europe has such a temperate climate.
Ocean water can hold more heat than air. For example, thermohaline currents (thermo = temperature, haline = salt) with warm, salt water sinking and rising. Salty water pushes not so salty water away. We get a current. Winds can also make ocean currents.
How do we track ocean currents?
Data marker buoy to monitor currents, sends out a radio signal we can follow and see where ocean currents are flowing.
But lately, satellites have gained a better picture of of Earth’s ocean movement.
NASA satellites like Poseidon and Jason observe ocean currents from space. These satellites have monitored ocean motion by measuring sea surface height.
Deep ocean currents are currently being researched using a fleet of underwater robots called Argo.
Why don’t rivers have salt?
When rain water falls on the land, it washes minerals and salt from the soil into lakes and rivers. But they don’t stay there.
They float downhill to an outlet at the nearest ocean. So lakes and rivers constantly have the minerals washed away. Oceans are salty because runoff transports minerals and salts from the surface.
With the exception of the Great Salt Lake which doesn’t have an outlet. Salt built up in the Great Salt Lake until its 4 times greater than oceans.
When ocean evaporates from heat, salt remains in the ocean and water rises. So unlike salty oceans, lakes and rivers constantly have the minerals washed away.
Fish rely on moving water for food and oxygen. That’s why aquariums have artificial currents moving water.
And living things need ocean currents for food, climate and transportation
Wind and salt keep ocean water moving.
For example, our ocean’s motion significantly affect Earth’s weather and climate.