How Many Joules of Solar Energy?
The intensity of electromagnetic waves from the sun is 1.4 KW/m2 just above the earth’s atmosphere. Eighty percent of this reaches the surface at noon on a clear summer day. Suppose you model your back as a 33 cm x 53 cm rectangle.
How many joules of solar energy fall on your back as you work on your tan for 1.4 h?
Intensity = 1.4 Kw/m 21.1 hr = 1.1 x 60= 66 minutes
1400 x .34 x .53 x 66 x 60
=9.99 x 105