Variable wind speed and evaporation rates: a practical and modelling exercise for high school physics and multi-strand science classes

Abstract

With the recent onset of drought conditions throughout many regions of Australia and across the world, a greater amount of interest has been placed on the measurement and modelling of evaporation rates in real world environments such as agricultural dams and drinking water reserves. Coinciding with this, substantial amounts of research work have been carried out detailing increasingly accurate methods to both measure and predict evaporative losses from water reserves along with the development of innovative techniques and technologies to suppress and mitigate water evaporation. Some examples of these techniques include fixed covers, floating covers, wind breaks along with chemical films and monolayers. The following practical exercise aims to give senior high school Physics and multi-strand science students an insight into how evaporation measurements can be made and compared with modelled data to verify their accuracy by employing local wind velocity, temperature (air and water) and water vapour (humidity) information. In addition to this, this exercise shows how publicly available chemical films based on substances such as silicon, cetyl alcohol and stearyl alcohol can be utilised to reduce evaporation. An analysis of film performance under varying wind velocities will be detailed for replication by students in the laboratory.