To check and confirm the small variations in the solar constant found at these two sites, Abbot received a grant from the National Geographic Society in March 1925 to select a site for a third solar observatory, equip it, and carry out observations for a few years.
42.
Because the surface area of a sphere is four times the cross-sectional surface area of a sphere ( i . e . the area of a circle ), the average TOA flux is one quarter of the solar constant and so is approximately 340 W / m?
43.
Where " P " is pressure, " W " is the solar constant ( W�m " 2 ), " c " is speed of light in vacuum, " R " is solar distance in AU treated as a dimensionless number, and & alpha; is the angle between the surface normal and the incident radiation.
44.
The "'solar constant "', a measure of flux density, is the amount of incoming solar electromagnetic radiation per unit area that would be incident on a plane perpendicular to the rays, at a distance of one solar activity, but recent recalibrations of the relevant satellite observations indicate a value closer to 1361 W / m?is more realistic.
