15. what is the solar altitude on the 4th of july in washington, d. c., at latitude 39"n? a.22.7 b.73.7 c.23.5 d.51° e.90° 16. through the whole year, the sun's declination migrates through a total of a. 23.5° b.30° с.470 d.66.5° e. 133

answer 15  correct option is b. 73.7°

answer 16 correct option is с. 47°

Explanation:

we know that on 4th july Northen hemisphere have summer and Washington, D.C also in Northen hemisphere

and sun present at 23.5° latitude

so latitude of sun is calculate as given figure below

= 90° - ( 39° - 23.5° )

= 74.5°

so correct option is b.73.7

this difference if because we take latitude 23.5°  that is approx on 24 july

but july 4 latitude will be some low

and

we know during summer declination angle is + 23.5 in N.H.

and during winder declination angle is - 23.5 in N.H.

and at spring and autumn sun is at equator

the declination angle change is

declination angle change = 27.5 + 27.5 = 47°

because the center-south is called the heart of the country