Construction of a Simple Domeless Net Radiometer for Demonstrating Energy Balance Concepts in a Laboratory Activity

Even though energy balance concepts are fundamental to solutions of problems in a number of disciplines in the agricultural and life sciences, they are seldom demonstrated in a laboratory activity. Here, we introduce a simple domeless net radiometer to demonstrate how the surface temperature of an object aboveground is regulated by the properties of the surfaces and environmental conditions. The device is based on the early designs of all-wave net radiometers and is composed of a foam disc with its opposing surfaces coated with either white or black paint. Temperatures of the disc's surfaces are monitored using thermocouple temperature sensors. Using a combination of solar irradiance, albedo of the ground surface, air temperature, and wind speed measurements, the temperatures of the disc's surfaces can be calculated by means of an energy balance model. We found good agreement between calculated and measured temperatures. In addition to demonstrate important physical concepts under natural outdoor conditions, we believe that the proposed laboratory activity will benefit students by allowing them to gain some experience and practical skills in working with environmental sensors, programming data acquisition systems, and analyzing data. Stimulating students' creativity as well as developing their analytical and problem-solving skills is another goal of the proposed activity.