From AMS Glossary
A collection of simultaneous meteorological measurements taken and recorded in a mountainous location.
The harshness of the high-mountain environment, the inaccessibility of sites, and the remoteness of these regions are special problems that have limited the availability of long-term records of mountain weather. These difficulties are compounded by the issue of representativeness of a measurement. Over flatter, simpler terrain, care is taken to place instrumentation in exposed locations where the measurement can be considered as representing a larger area. Barry (1992) defines at least three types of situations in the mountains: "summit, slope, and valley bottom— apart from considerations of slope orientation, slope angle, topographic screening, and irregularities of small-scale relief." Thus it is very difficult, perhaps inappropriate, to claim representativeness for a single observation, and one must interpret mountain observations with great caution. Barry further states, "These factors necessitate either a very dense network of stations or some other approach to determining mountain climate. In the future, the use of ground-based and satellite remote sensors combined with intensive case studies of particular phenomena, may provide the best solution."
Barry, R. G. 1992. Mountain Weather and Climate. 2nd ed., Routledge, London, . 9–10.