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The 1370 W/m2 is at the top of the atmosphere. From Jerry Marion's 'Energy in Perspective': "At the top of the atmosphere, solar energy is incident at an average rate of approximately 1.4 kW/m2. The total amount of energy received by the Earth from the Sun in a year amounts to 1.6x10^18 kWh. Because of the absorption in the atmosphere and reflection from clouds, only about half of the incident energy reaches the surface of the Earth, and averaged over a day, the solar power is about 0.2 kW/m^2."
At any particular moment the irradiance at the surface is going to depend on the day of the year, the hour of the day, and of course the weather conditions. I suspect there are tables and know there are 'days of sunshine' tables by location.
rwt
On 5/21/2014 10:04 AM, Anthony Lapinski wrote:
The solar constant is around 1370 W/m2. I believe this is the average
value over the entire Earth in one year. I have two questions.
1. How can I find the approximate value on a given day at a given location
(latitude)? Is there some formula or way to estimate? I realize this might
not be easy.
which leads to:
2. Is there a "simple" experiment kids can do to measure the solar
constant (solar cell, heating water, etc.)?
This has some good concepts for energy, heat, and optics in both physics
and astronomy.
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