Question

why we Sprinkle water on the roof or open ground on a hot sunny day?​

Answer 1

Answer:

to minimise the hotness of that substance

Answer 2

When people sprinkle water on hot and dry roof on a sunny day, that water evaporates by taking energy from the ground, roof and surroundings. The evaporation of water causes a cooling effect because the large latent heat of vaporization of water helps to cool the hot surface.