Explain the process- Rainwater harvesting?

Explanation

Mole fraction of component 1 in vapour phase, `y_1=P_1/(P_("total"))`
Mole fraction of component 2 in vapour phase, `y_2= (P_2)/(P_("total"))`
In general `y_1 = ("Partial vapour pressure of component")/("Total vapour pressure")`