Calculate the loss of water per hour per unit area from a horizonal water surface over which air is flowing at $2\mathrm{.}5$ m$/$sec$.$ The total pressure is $0\mathrm{.}98$kg$/$cm and partial pressure of water vapour in it is $10$mm of Hg$.$ The length of the water surface in the wind direction is $2$m$.$ The relative humidity is $33\mathrm{.}3\%.$ The diffusion coefficient at the average temperature is $7$cm per hour. Kinematic viscosity of air at the average temperature is $1$ x$10$ cm$/$h$.$