Most advances in measuring the natural environment that have taken place over the last three to four decades have come about through developments in microelectronic chip technology. This has led to the now ubiquitous PC and to an abundance of other devices including (relevant to us) data loggers and satellites able to both generate images and relay data from ground stations to a distant base.

Developments in sensor technology for in situ measurements of the environment over the same period have been relatively modest in comparison; when they have occurred, they have usually been driven by the same microelectronic technology. Much of the actual ‘front-end’ of the sensor technology has, however, changed remarkably little. We are still using cups and vanes to measure wind, but with electrical sensors attached (although sonic anemometers may slowly replace them if costs can be brought down further). Temperature is still measured by electrical resistance thermometers in small screens. Despite being able to measure solar radiation with precision, sunshine duration measurements are still in demand, although sensed electronically. A most useful microelectronic development has been the introduction of general purpose photo diodes which can also be used as cheap, but slightly less precise, solar radiation sensors. Thermal solarimeters, the most accurate, have remained virtually unchanged since 1965, as have net radiometers. Humidity is still widely measured by the wet and dry method although thin-film capacitive sensors are now replacing it (developed originally for radiosondes).