Global Systems
-Natural Influences on Climate

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Weather and Climate

– describes the

  • Wind

Created by interactions between the , hydrosphere and .

– long term averages of weather conditions. Climate changes occur when certain things influence the weather over longer periods of time.

Influences on Climate

Energy from is the major influence on climate.  But there are other factors

Surface of the Earth

Energy can be reflected back into space from things such as and (even deserts)

Gasses in the Atmosphere

The main gasses in the Earth’s atmosphere are and . These do not affect the absorbtion of energy from the sun.  However, there are other gasses that absorb energy (long waves of heat as it reflects off the Earth):

  • Carbon dioxide
  • Nitrous oxide

These gasses are called . And can have an effect of warming the earth close to its surface. This is called the .

Orientation of the Earth

As the earth rotates and are with it. But the most influence on moving air and water has to do with . The tilting of the Earth on its axis alters where the most sun is shining and changes the temperature as a result.

Ocean Currents

These are bodies of water in the oceans.  They are caused by

  • Wind
  • Rotation of the earth
  • pull of the sun and moon

There are two types:

Major surface currents

Caused by wind, they create (circular patterns of current). These flow in the northern hemisphere and anticlockwise in the hemisphere.

Deep currents

Start in the and then carry very water towards the tropics.

Currents and Climate

Surface currents and deeper currents interact.  This produces circulation. These distribute heat around the earth in what is known as the belt.

The Gulf Stream

Part of the thermohaline is the , which warms Europe (UK and Norway) more than and Canada at similar latitudes.

Australia’s Climate

Two factors affect Australia’s climate

  • The Oscillation
  • The Dipole

Southern Oscillation

Normal situation is no or

The Southern Oscillation Index (measure of the difference in between and ). Normal conditions the SOI is close to zero.

    • SOI is strongly
    • SOI is strongly

    • During El Nino – abnormally in Queensland and NSW.
    • During El Nina – abnormally in Queensland and NSW

Indian Ocean Dipole

  • Result of differences in water temperature between the eastern and western regions of the
  • Change is not
  • If IOD is (warmer in western ocean) then rainfall in central Australia is
  • IOD is then in rainfall in central Australia.

Changing Climate

It has been demonstrated that the climate in Australia has changed in the past 1,000,000 or so as it between glacial and interglacial periods.
It would appear that the current interglacial period began about ago.

As ice ages approach the ice caps and sea levels . In the past Australia would have been joined to New Guinea and Tasmania

Global warming

The period between ice ages is a period of , when sea levels increase and ice caps decrease. It is suggested that the earth should be due to move into a position of global .

Evidence for Climate Change

Evidence for past climate changes come from a a of sources

Glaciers

Glaciers advance and retreat with changes.  As the glacier advances rocks valleys. As they retreat theare left.

Ice Cores

As changes in climate occur the snow falls in permanent frost areas are placed down in along with and and levels in the layers which gives a history of what might have happened in the past and possible .

Pollen Analysis

Pollen is not broken down quickly. As climate changes so does the vegetation.  The types of pollen indicate the at any time.

Sea Level Changes

The distribution of sedimentary rocks shows occurring in them.  Often we find fossils of sea creatures on that has been dry for .

 

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