V m 2 W -1 with a response time of about 5 seconds. The Moll-Gorczynski solarimeter is composed of a blackened thermopile constructed almost identically to the heat flux plate described in lab 2. Internal circuitry compensates for variations in the temperature of the instrument, which can influence the thermopile output. Although output is in temperature units, this instrument actually measures the flux of IR radiation emitted by the surface at which it is pointed. As with all thermopiles, those within this instrument measures the net exchange with the environment, including the instrument housing.
Total radiation equals the sum of solar and terrestrial radiation.
The Fritschen radiometer contains a blackened thermopile enclosed within a polyethylene dome which transmits all wavelengths of radiation. Such all-wave radiometers have both their lower and upper surfaces of the thermopile exposed to the surroundings, and the output of the instrument is proportional to differences in temperature, and thus in the amount of incoming radiation, between the two sides. At night, the net infrared radiation is measured between the ground and sky, and during the day, the net total radiation, or the difference in total sky and ground radiation is measured. The height of the instrument above the ground influences the reading since it determines its view of the surroundings. For example, if the sensor is high above the level of the vegetation the incoming IR radiation includes the radiation emitted by both the ground and the vegetation in view of the lower side on the instrument.