• 30 Nov 07
  

  amandadouglas

  radiation solar

• 23 Nov 07
  

  bronwyn123

  energy from links radiant sun the

  • RADIANT ENERGY FROM THE SUN

    Radiant energy is also  called electromagnetic energy. Almost every reaction that happens on the surface  of the Earth is the result of energy coming to the Earth from the Sun. Radiant  energy is also called electromagnetic energy because it is made up of two  combined fields. One of the fields is electrical and the other is magnetic.  
    
    One other thing to remember: when we talk about incoming radiation, we  don't always mean radiation like X-rays, or radioactivity. Light is radiation of  some kind. All light is one form of radiation or another. Just keep that in  mind.
    
     

    CONSTANT OUTPUT OF ENERGY

    Solar radiation is light energy from the Sun.  So you've got the Sun. Millions of kilometers away from the Earth it sits there  with all sorts of nuclear reactions going on. It's constantly  giving off a huge amount of energy and radiation. By the time the energy and  light reach Earth, there isn't much energy left. Scientists have figured out  something called a solar constant. The constant is the amount  of radiation that actually hits the Earth. They say it's about 29.4 MJ  (Megajoules, a unit of energy) for every square meter for each day.
    
     

    CONSTANT INPUT OF ENERGY

     The flow of energy to the Earth is constant. That constant flow is just the  amount of EM radiation hitting the outside of the atmosphere. The energy from  the Sun has changed by the time it hits the surface of the Earth. At the top of  the atmosphere you have the 29.4 MJ. We only see about 17 MJ of energy at the  surface of the Earth. Something had to happen to the EM radiation between the  top of the atmosphere and the surface of the Earth. Energy and certain types of  EM radiation (Infrared and Ultra Violet) have  been filtered away.
    
     

    NOT ALWAYS CONSTANT AT THE SURFACE

    Several factors determine the amount  of radiant energy hitting the Earth. Our planet is a specific distance from the  Sun. Even though we have a slightly elliptical orbit around the  Sun, we can expect a certain amount of energy to hit our planet. If we were  closer there would be more energy hitting our atmosphere and if we were further  away there would be less energy. We also have a Sun with special  characteristics. As our Sun gets older, it will begin to expand. That increase  in size is going to affect the amount of radiant energy hitting our atmosphere.  The solar constant is based on the Sun's activity now.
    
    

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