Global CurrentsGlobal CurrentsWeather DynamicsWeather Dynamics

Science 10Science 10

Previous KnowledgePrevious Knowledge

We already know that uneven warming of the We already know that uneven warming of the Earth results in different atmospheric Earth results in different atmospheric temperaturestemperatures

When air warms, it becomes less dense. When air warms, it becomes less dense. When air cools, it becomes more denseWhen air cools, it becomes more dense Fluids move from HIGH to LOW pressure. Fluids move from HIGH to LOW pressure.

Therefore, cool air moves towards/under Therefore, cool air moves towards/under warm air pushing it awaywarm air pushing it away

Latitude/ LongitudeLatitude/ Longitude

Latitude is a measure North or South Latitude is a measure North or South of the equatorof the equator

Longitude is a measure east or west Longitude is a measure east or west from a reference line called the from a reference line called the prime meridianprime meridian..

Warming of the EarthWarming of the Earth

Temperatures at the equator are Temperatures at the equator are much warmer than the Poles. much warmer than the Poles.

Because of this, air at equator Because of this, air at equator becomes much warmer. HOW?becomes much warmer. HOW?

DensityDensity

The very cold air at the poles will push The very cold air at the poles will push down towards the equator.down towards the equator.

It will slip underneath the warm air and It will slip underneath the warm air and push the air up and away, towards the push the air up and away, towards the colder regionscolder regions

Coriolis EffectCoriolis Effect

The influence of Earth’s rotation on air, The influence of Earth’s rotation on air, or any object moving on Earth’s surfaceor any object moving on Earth’s surface

We know the atmosphere is moving We know the atmosphere is moving withwith the Earth because we can not the Earth because we can not feelfeel the the atmosphereatmosphere

Prevailing WesterliesPrevailing Westerlies

In the central part of the Northern In the central part of the Northern Hemisphere, including most of Hemisphere, including most of Canada and the US, the Coriolis Canada and the US, the Coriolis Effect causes the winds to blow from Effect causes the winds to blow from WEST to EASTWEST to EAST

Eastern Trade WindsEastern Trade Winds

Not all winds blow from west to east. Not all winds blow from west to east.

In certain parts of the globe, the In certain parts of the globe, the Coriolis Effect results in winds Coriolis Effect results in winds moving from the EAST to the WESTmoving from the EAST to the WEST

Jet StreamsJet Streams

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

They are caused by the contact of cold They are caused by the contact of cold and warm airand warm air

Found between the ZONES of the globe Found between the ZONES of the globe (polar/temperate, temperate/tropical)(polar/temperate, temperate/tropical)

Polar Jet StreamPolar Jet Stream

Affects Canadian weatherAffects Canadian weather Meets at the Polar and Temperate zonesMeets at the Polar and Temperate zones Prevailing Prevailing westerliesI westerliesI meet polar meet polar

easterlieseasterlies Cold air will push under the warmer Cold air will push under the warmer

westerlies and cause it to risewesterlies and cause it to rise No boundaries (hills, etc) = really fastNo boundaries (hills, etc) = really fast

Jet StreamsJet Streams

Speeds vary from 100km/hr to 300km/hrSpeeds vary from 100km/hr to 300km/hr ~ few hundred kilometers wide~ few hundred kilometers wide Not a perfect circle; continuously Not a perfect circle; continuously

meander to the north and southmeander to the north and south Areas ABOVE are cold, areas BELOW are Areas ABOVE are cold, areas BELOW are

warmwarm

Ocean CurrentsOcean Currents

Follow the same properties of Follow the same properties of atmospheric currentsatmospheric currents

Warm water = less denseWarm water = less dense Cold Water = more denseCold Water = more dense Fresh Water = less denseFresh Water = less dense Salt Water (salinity) = more denseSalt Water (salinity) = more dense

Surface/ Deep OceanSurface/ Deep Ocean

Surface currents run on the top of Surface currents run on the top of the ocean and are started by WIND. the ocean and are started by WIND. The shape of the currents is affected The shape of the currents is affected by the rotation of the Earth/shape of by the rotation of the Earth/shape of the continentsthe continents

Deep ocean currents run at the Deep ocean currents run at the bottom and are affected by density, bottom and are affected by density, temperature, and salinitytemperature, and salinity

MovementMovement

Thermohaline CirculationThermohaline Circulation

The rotation of the planet also affects The rotation of the planet also affects currentscurrents

Coriolis EffectCoriolis Effect

Waters will be affected in the same Waters will be affected in the same way air currents will beway air currents will be

In the Northern Hemisphere, water In the Northern Hemisphere, water will move will move clockwiseclockwise. In the southern . In the southern hemisphere, waters will move hemisphere, waters will move counter-clockwisecounter-clockwise

GyresGyres

These currents are deflected by the These currents are deflected by the continents, causing them to bend and continents, causing them to bend and create large current loops called create large current loops called circulation gyres.circulation gyres.

Affecting ClimateAffecting Climate

Colder currents will release less Colder currents will release less vapour into the atmosphere and will vapour into the atmosphere and will therefore result in a dryer climatetherefore result in a dryer climate

This is where you will find the This is where you will find the majority of your deserts.majority of your deserts.

Ex. Bathroom steaming up. Ex. Bathroom steaming up.