At a certain location $(25{47}^{\text{'}}N,75{39}^{\text{'}}E)$ in India, an unshaded pyranometer $($kept

on a horizontal surface$)$ and a pyrheliometer record $695$ and $721\frac{W}{m^2}$ respectively

at $1000$ h $($IST$)$ on September $15.$ A flat$-$plate collector is installed with a tilt of

$13$ and is oriented east of south at an angle of $35.$ Calculate the flux incident on

the collector. Given that the reflectivity of the surfaces surrounding the collector is

$0\mathrm{.}2.$

What is the percentage reduction in the value of the flux incident on the collector

due to the presence of the atmosphere?