Global Winds and Ocean Currents Ocean Currents are created by global winds. Ocean Currents are created by global winds. Global winds are created by the uneven heating of the Earth. Global winds are created by the uneven heating of the Earth. Why doesn’t the Earth heat evenly? Why doesn’t the Earth heat evenly? 1. The planet is a sphere1. The planet is a sphere 2. Parts of the planet are covered by land and parts are covered by water.2. Parts of the planet are covered by land and parts are covered by water.

Only the part of the Earth that is in a direct line with the sun (the tropics) gets the full force of the solar radiation. As you move north and south from the tropics the solar radiation comes in at an angle and thus has less heat. The least amount being at the poles (north and south)

The solar radiation hitting the tropics heats the air and causes it to rise. The air hits the upper atmosphere causing the air to move north and south. The air cools, becoming more dense causing it to sink. EquatorSouth North cold air hot air

The hot air rising leaves a void which is filled by air, which we call wind. These circular motions of air are called cells. EquatorSouth North cold air hot air Wind

The rising air is a low pressure system. The sinking air is a high pressure system. area of low pressure area of high pressure Notice that the air moves away from an area of high pressure and towards an area of low pressure.

If viewed from above the pressure systems would appear like this: H L

Global winds created by the cells

Coriolis Effect Everything moving in the northern hemisphere veers to the right. Everything in the southern hemisphere veers to the left. This is called the Coriolis Effect and it is due to the rotation of the Earth.

The rotation of the Earth causes things that are moving to veer. This is known as the Coriolis effect

Because of the Coriolis effect everything moving in the northern hemisphere veers to the right or spins clockwise everything moving in the southern hemisphere veers to the left or spins counterclockwise

Coriolis effect on global winds

As a result of the Coriolis effect there are global winds that circulate around the world. Winds are named for the direction from which they originate.

What are winds that blow from the northwest to the southeast called? From where do trade winds get their name? Equatorial Doldrums are areas above the equator with little or no wind. Why do these areas lack winds? What are Horse Latitudes and what do they have to do with horses?

Global Winds Create Currents 1. Trade winds create a current that travels from east to west The water deflects and travels north. 3. The Westerlies cause the water to go east.

Similar currents occur in the southern hemisphere except they occur in reverse (counter clockwise) One major difference is that there is a current that connects all of the oceans. Similar currents occur in the other oceans. Draw them in.

The currents that run north and south parallel to the land are called continental boundary currents The currents that run parallel to the equator are called equatorial currents (north and south) The current connecting all of the oceans is called the West Wind Belt The circular motion of the water is called a gyre

There are also counter currents which are generally not as strong as the other currents. Many of the currents have other names such as A. The Gulf Stream B. The California Current C. The Peru Current A B. C.

1. 2. The California (1) and Peru (2) currents bring cold water to well lit areas which creates great conditions for phytoplankton (plant plankton)

Upwelling Upwelling is vertical water movement. Water brought up from the bottom of the ocean to the surface. It occurs along the California coast for a couple of reasons: 1) The California current veers to the right forcing water away from the coast and 2) During summer months high pressure systems cause winds (Santa Ana) to blow offshore forcing more water away from the coast. The cold water from below comes up (upwells) and fills the void.

offshore wind Upwelling brings up cold nutrient rich water

2. 1. A change in pressure systems occurs in the south Pacific which causes the equatorial counter current to become stronger thus the Peru current becomes weaker. Warm water enters the Peruvian coast causing plankton to die and the fish to either leave or die. =El Nino

White represents warm temperatures Normal El Nino

Coriolis effect on global winds