- #1
jones123
- 10
- 0
Hi all,
I have some difficulties understanding a formula for calculating the incidence angle for incoming solar radiation on a sloping surface. I found that:
angle of incidence calculated as cos(j) = sin((pi/2)-surface slope)*sin(altitude angle) + cos((pi/2)-surface slope)*cos(altitude angle)*(cos(surface aspect - azimuth angle))
However, in my textbook it says "The angle between the sun’s projection on the horizontal plane and the plane of the gridcell’s slope is calculated as: azimuth angle * tan(surface slope + cos(azimuth angle - surface aspect))"
Can anyone explain me what the difference between these two formulas is and how they are related?
Thanks in advance!
I have some difficulties understanding a formula for calculating the incidence angle for incoming solar radiation on a sloping surface. I found that:
angle of incidence calculated as cos(j) = sin((pi/2)-surface slope)*sin(altitude angle) + cos((pi/2)-surface slope)*cos(altitude angle)*(cos(surface aspect - azimuth angle))
However, in my textbook it says "The angle between the sun’s projection on the horizontal plane and the plane of the gridcell’s slope is calculated as: azimuth angle * tan(surface slope + cos(azimuth angle - surface aspect))"
Can anyone explain me what the difference between these two formulas is and how they are related?
Thanks in advance!