Sun Angles

Impact the amount of
Insolation
 Daylight Hours


Seasonal
October – March



Zenith Angle

April – September
• High - Sun
Latitude where sun is
directly overhead (90°)
• Sub Solar Point
• Low – Sun

Solar declination

Angle between 90°
and sun at noon
Sun Angle

Angle of the sun
above the horizon at
noon
Sun Angles

Zenith Angle + Sun
Angle = 90°
 SO


What is Tuscaloosa’s
noon sun angle on
June 21st?
Let’s practice

Step 1


Determine declination
of sun for that date
Step 2

Find noon sun angle
• Difference in ° between
location’s latitude and
SS point then subtract
from 90
The
Analemma
Daylight Hours

How does sun angle
impact the amount of
daylight hours at
different latitudes?
 Online calculator
Solar Intensity

Intensity = Sin (A)


Sin = sine
A = sun angle

90 = 100% efficiency
 80 = 98%

45 = 71%
 20 = 34%
Run Applet
Insolation by Latitude
NET RADIATION