# How do you determine the angle of sunlight?

Jul 19, 2016

At noon, this angle is given by
$a r c \tan$ (length of your horizontal shadow)/(your vertical height)

#### Explanation:

Defining angle of sunlight as angle of incidence of light rays

from Sun, this angle is the angle 'a' that the sunlight-direction makes

with the vertical. When sunlight strikes right from overhead, a = 0.

At sunrise and sunset on any day, sunlight strikes horizontally. So,

this angle is ${90}^{o}$.

At noon ( the instant midway between sunrise and sunset), this angle

minimum.

If you measure the length of the shadow at noon as L against your

height H,

$\tan a = \frac{L}{H}$, and so,#

$a = a r c \tan \left(\frac{L}{H}\right)$

Of course, this varies between $l a t i t u \mathrm{de} \pm {23.4}^{o}$, in a year