Coriolis Effect

• explain how the rotation of Earth influences movement of objects that are not connected to the surface

• describe how the Coriolis Effect deflects moving parcels of air in the northern and southern hemispheres

Key Words

Coriolis effect deflection

currents

Everything on Earth moves at the speed the Earth rotates.

This speed is different for objects at different latitudes.

Coriolis Effect

Objects (air, oceans, airplanes) not rigidly attached to the Earth will appear to move along a curved path even though they may actually be travelling in a straight line.

Northern hemisphere – things appear to turn right

Southern hemisphere – things appear to turn left.

Corliolis deflection

Wind and Convection Currents

Air is colder near the poles and warmer near the equator.

When air warms, the particles move apart and rise. Warm air is less dense. Less air density means low pressure.

Particles of cold air are close together. Cool air is more dense and has a higher pressure and sinks.

cold

hot

Fluids (liquid, gas) move from areas of high pressure to areas of low pressure.

This pressure movement of cold and warm air creates CONVECTION CELLS.

Cold, dense air at the poles moves along the Earth’s surface towards the equator.

Warm air at the equator is forced up and away north and south.

CONVECTION CELLS

Convection cells that cover the Earth are also affected by the Corliolis effect.

Convection cell winds affect large areas and are called prevailing winds.

Wind is new air from a different location that has a different speed then the air in that spot.

Where convection cells meet. Jet streams are formed.

Jet streams are ribbons of extremely fast moving air near the top of the troposphere.

The Coriolis effect of the Earth’s rotation is greatest at the poles.

The amount of deflection decreases as latitude decreases, until it is zero at the equator.

Moving toward poles – lead earth's rotation – headed to regions where the earth's rotational speed is slower – curves East.

Moving toward equator – lag earth's rotation – headed to regions where the earth's rotational speed is faster – curves West.

Lower atmosphere – contacts the surface of the Earth. Friction between air and land drags the air at the same speed as surface rotation.

Upper atmosphere – not fixed to the Earth’s surface, does not move at the same speed or direction as the Earth’s surface.

(Northeast) Trade winds - between 30 ° North latitude the equator. Shift from the East towards the West.

Westerlies - between 30 ° and 60 ° latitude. Shifts from West to East.

Polar Easterlies - cold air near the poles (above 60 °) sinks and moves towards the equator. Corliolis effect shifts the winds from East toWest.