A UV-B meter having sharply increasing sensitivity with decreasing wavelength can be shown to well represent a large number of known biological action spectra. The accuracy of the meter, which is temperature stabilized, and its long term stability enable accurate UV and UV trend information to be obtained. The meter is readily calibrated in the laboratory or in the field since it has cosine law agreement. Spectral responses between meters are negligibly different. The meter requires very little maintenance. An on-board computer stores months of data and can be remotely interrogated. The initial cost is low making an extensive network possible. The redundancy of a network enables long term UV trend determinations to be made with even greater confidence than that from a single meter.