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Please help assign due 2marrow effective radiative temperature

  1. Jan 24, 2010 #1
    . The problem statement, all variables and given/known data

    It is believed that in the Archeaneon (2.5-4 billion years ago) the sun’s radiative output was 30% less than it is today.

    (i) What would the temperature of the sun have been at that time?

    (ii) At what wavelength would the peak emission from the sun have been?

    (iii) Ignoring the effects of the atmosphere, what would the temperature of the Earth have been at this time (i.e. the effective radiative temperature)? Assume that the Earth’s albedo was 0.3, the same as today.


    2. Relevant equations
    Boltzman equation
    wiens law

    3. The attempt at a solution

    a)T= 4th root[5143824/(5.67*10^-8)]
    t=5488.14K

    b)detlamax=2897/5488.147
    =0.527

    I DONT GET PART 3 PLEASE HELP MEE!! MY ASSIGNMENT IS DUE TOMARROW! PLEASE
     
  2. jcsd
  3. Jan 25, 2010 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    You will have to do a better job of explaining your work in parts 1 and 2.

    To do part 3, you have to determine what amount of radiation the earth currently receives / unit time and then reduce it by 30%. You know that the earth must radiate that same amount of energy /unit time (on average). From that, apply the Stefan-Boltzmann law to determine its temperature.

    AM
     
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