In this section, you will learn: zz how unequal heating of the Earth’s surface leads to the movements of ocean currents.
Current Gulf Stream
North Atlantic Drift Labrador Current
Ocean waters are always moving. The movement of water is referred to as a current. A current is like a river flowing though the ocean. Ocean currents occur due to:
• Differences in temperature • The Earth rotating on its axis • Wind
Currents can be warm or cold depending on where they flow from.
Warm currents
Currents flowing from the equator are warm. The Gulf Stream originates in the Gulf of Mexico and turns north-eastwards into the Atlantic Ocean, where it splits to form the warm North Atlantic Drift (NAD) and the cold Canary Current. The NAD flows past the west coast of Ireland where it helps to keep ports ice-free.
Cold currents
Cold currents flow from areas in high latitudes towards the equator. The Labrador Current, which flows south along the coast of north-east America, reduces the temperature of the ocean and many ports freeze over as a result.
Labrador
N. Atlantic Drift
N. Atlantic Drift
Canary Gulf Stream
( Figure 13.8 Major ocean currents
DID YOU KNOW? The Gulf Stream is 100 km wide, about 1 km deep and moves at a speed of 3.5 kph.
Key
Warm current Cold current
(i) Name one warm current. (ii) Name one cold current. (iii) What is a current? (iv) What current keeps Ireland’s coast ice-free? How?
/ I understand the heating of the Earth’s surface and how it results in ocean currents. 231
