Name:                                                                                                  Date:                                                  EN       

The Greenhouse Effect

greenhouse.tiffWhen light enters a greenhouse it warms the floor and the air inside.  In this way, insolation is changed into heat energy.  The heated objects emit radiation in the invisible infrared part of the spectrum.  But, the heat (infrared) radiation is unable to escape because heat rays will not pass through the glass walls and roof.  So a greenhouse traps heat energy because the light energy is changed into longer wavelength infrared waves (heat).


1.  Glass is transparent to                                                     energy, but it


will not allow                                                     energy to pass through.


Earth’s atmosphere acts in the same way.  Visible light from the sun penetrates to the ground, where it warms the Earth.  This warming causes an increase in the infrared (heat) radiation given off by the Earth.  But the atmosphere absorbs heat rays, so its temperature increases.  The natural effect of the atmosphere keeping Earth a comfortable temperature for life as we know it is called the Greenhouse Effect.


Carbon dioxide and water vapor are the two gases that absorb most of the Earth’s heat radiation.  Our increasing use of fossil fuels, like oil, natural gas and coal, is adding tons of carbon dioxide to the atmosphere each day.  Scientists believe that the increased carbon dioxide will warm the Earth causing uncontrollable climate changes.  These changes are referred to as Global Warming.  This could cause dramatic changes in rainfall in vital agricultural areas, and melting of polar ice caps could flood coastal cites around the world.


2.     According to the diagram to the left, what portion of the Earth’s infrared radiation is absorbed by the atmosphere?       


3.     What gases in the air absorb heat radiation?




4.     What is the Greenhouse Effect?



5.     What is Global Warming?