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Energy transfer by heating

Heat can be transferred from place to place by conduction [conduction: The transfer of heat energy through a material - without the material itself moving. ], convection [convection: The transfer of heat energy through a moving liquid or gas. ] and radiation [infrared radiation: Electromagnetic radiation emitted from a hot object. ]. Dark matt surfaces are better at absorbing heat energy than light shiny surfaces. Heat energy can be lost from homes in many different ways and there are ways of reducing these heat losses.

The modern atmosphere

You need to know the proportions of the main gases in the atmosphere.

The Earth’s atmosphere has remained much the same for the past 200 million years. The pie chart shows the proportions of the main gases in the atmosphere.

air is made up of nitrogen (78%), oxygen (21%) and other gases (1%)

The composition of air

The two main gases are both elements and account for about 99 percent of the gases in the atmosphere. They are:

  • about 4/5 or 80 percent nitrogen (a relatively unreactive gas)
  • about 1/5 or 20 percent oxygen (the gas that allows animals and plants to respire and for fuels to burn)

The remaining gases, such as carbon dioxide, water vapour and noble gases such as argon, are found in much smaller proportions.

Back to Changes in the Earth and its atmosphere index

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