Appendix A. Definitions

An "element" is a measurable time-varying quantity. The most familiar elements are meteorological things like temperature, precipitation, relative humidity, etc. In addition to these meteorological elements, scientists also often measure and track quantities related to the equipment used to measure meteorological elements, such as battery voltage, fan speed, or anything else related to the measuring equipment. These other measured quantities are also called elements; sometimes they are called "diagnostic elements" to distinguish them from meterological elements.

A "station" is a fixed location from which some elements are measured on an ongoing basis for some period of time.

A station's "period of record" is the period of time for which elements have been measured at that station.

A "network" is a collection of stations.