Glossary of "Environmental Science: Earth as a Living Planet (2nd ed.)" by Botkin & Keller (1998)
- observations: Information obtained through one or more of the five senses or through instruments that extend the senses. For example, some remote sensing instruments measure infrared intensity, which we do not see, and convert the measurement into colors, which we do see.
- Botkin, D. B. & Keller, E. A. 1998. Environmental Science: Earth as a Living Planet, 2nd ed. -xxxxii + 649 pp. John Wiley & Sons, Inc., New York.