
256 Principles of Sustainable Energy Systems
© 2008 Taylor & Francis Group, LLC
On February 1, day number, n = 32. Therefore, from Equation 5.23, the declination is
δ
s
=
+
=− °
°
23 45
360 284 32
17 5.sin
()
.
At solar noon, h
s
= 0. Therefore,
sincos coscoshsin coscos cosh sinsinααδδ=δLLL
ss ss s
=−
+−cos( .)cos( .)cos( )sin(.)sin(.)29 7175 0297 17 5
or α = 42.8°
sin a
s
=
−
=
cos( .)sin( )
17
0
or a
s
= 0
At solar noon, α can also be found as
=−−
L
s
=− +=90 29 7175 42 8|. .| .
hh L
ss sr
or tantan=± −⋅
−
cos[ ]
1
δ
s
=± −⋅
=±
−
costan(.)tan(.
1
29 7175 79 65
Time from solarnoon (79.65 /degree)
= 319 minor(5h19 mi
=±
±±
)( min4
nn)
Sunris ...