What Is The Natural Greenhouse Effect?

Learn the basics about the natural greenhouse effect. The atmosphere helps to keep our planet warm by making it harder for the energy we get from the sun to escape back to the universe. Our atmosphere is held to the earth by the force of gravity. Visible light gets straight through our transparent atmosphere and is partly absorbed by the earth which gets hot. Hot things radiate infra red rays. Although visible light got through the atmosphere, the infra red radiation coming from the earth finds it more difficult to get through. So the atmosphere acts a bit like glass letting visible light through to warm the earth but some of the heat (or infra-red) radiation now given off gets absorbed by certain gases in the atmosphere, called greenhouse gases. In this way the earth is kept warm and we say there is a natural greenhouse effect. The two natural gases that absorb infra-red are water vapour and carbon dioxide. Clouds, made of water droplets, insulate night skies in the winter, but without the clouds the heat gets away and frost forms. Before the world became industrialised by burning fossil fuels such as coal oil and natural gas, the carbon dioxide concentration in the atmosphere was about 0.028% tiny compared with O=O at 21% and NN at 78%, but enough to keep us warm. Without this natural blanket of insulating gas the earth would be too cold to support life as we know it.