At the distance the earth is from the sun, it has an irradiance of about 1370 Watts per square meter. Also statistically speaking, only about 70% of the energy that hits earth is absorbed. Therefore, the sun’s energy that enters earth’s atmosphere is around 960 Wm-2. Yet another factor is the fact that only a fourth of the earth’s surface area receives that load at any given time. That will then condense our Watts per square meter to 240. So the net incoming energy is 240 Wm-2. Now we need the radiative energy flux for the earth. With the earth’s average temperature at 288 kelvin, the equation σT4 gives us a radiative energy flux of 390 Wm-2 (note that σ = the Boltzman constant = 5.670373×10−8 W m−2 K−4 and T= temperature). However, this 390 Wm-2 does not leave earth’s energy in balance since the income is 240 Wm-2. By simply applying the income energy value (240 Wm-2) to σT4, we can calculate earth’s average temperature which comes out to 255 kelvin or -18 Celsius. Hold on! Negative 18 Celsius cannot be write considering zero in Celsius is the water freezing point and most or the earth isn’t frozen over. Actually, by averaging recorded temperatures throughout the earth’s surface, the average surface temperature is generally considered to be 15 Celsius. That is a 33 difference that is the result of none other than the greenhouse effect. Amazing! So far the greenhouse effect has increased the earth’s temperature from what would be considered an extreme temperature for living conditions today. Perhaps the greenhouse effect could be a good thing after all. Again, eventually this greenhouse effect could be a major problem. One day, perhaps, the extreme temperature will be on the other side of the spectrum, but it may not be such an extreme temperature at that time… only time will
At the distance the earth is from the sun, it has an irradiance of about 1370 Watts per square meter. Also statistically speaking, only about 70% of the energy that hits earth is absorbed. Therefore, the sun’s energy that enters earth’s atmosphere is around 960 Wm-2. Yet another factor is the fact that only a fourth of the earth’s surface area receives that load at any given time. That will then condense our Watts per square meter to 240. So the net incoming energy is 240 Wm-2. Now we need the radiative energy flux for the earth. With the earth’s average temperature at 288 kelvin, the equation σT4 gives us a radiative energy flux of 390 Wm-2 (note that σ = the Boltzman constant = 5.670373×10−8 W m−2 K−4 and T= temperature). However, this 390 Wm-2 does not leave earth’s energy in balance since the income is 240 Wm-2. By simply applying the income energy value (240 Wm-2) to σT4, we can calculate earth’s average temperature which comes out to 255 kelvin or -18 Celsius. Hold on! Negative 18 Celsius cannot be write considering zero in Celsius is the water freezing point and most or the earth isn’t frozen over. Actually, by averaging recorded temperatures throughout the earth’s surface, the average surface temperature is generally considered to be 15 Celsius. That is a 33 difference that is the result of none other than the greenhouse effect. Amazing! So far the greenhouse effect has increased the earth’s temperature from what would be considered an extreme temperature for living conditions today. Perhaps the greenhouse effect could be a good thing after all. Again, eventually this greenhouse effect could be a major problem. One day, perhaps, the extreme temperature will be on the other side of the spectrum, but it may not be such an extreme temperature at that time… only time will