Climatology

Paleoclimatology

Paleoclimatology is an important subdiscipline of climatology that focuses on the examination of past climates on Earth. Roughly, the temporal period for studying past climates is considered to span beyond the intervals that instrumental data records provide, ranging from approximately 50 years ago to several million years ago and earlier. This type of climatological study is aimed at uncovering the extent to which climate has changed throughout geologic time while revealing the internal and external influences (of natural and anthropogenic origin) on past climate conditions and climate change. Examples of some of these influences include variations in Earth's orbital parameters, plate tectonics, volcanic [Page 472]eruptions, and the extensive logging and clear-cutting practices of the early North American settlers. In addition, paleoclimatologists often evaluate how climate variability in the distant past may have assisted in the formation, arrangement, and deformation of the structure of Earth's present and past landforms and water bodies as well as atmospheric composition. For instance, extensive periods of wetter than average conditions in the Pleistocene led to the creation of many paleo-lakes, which are mostly dried up at present. To assist many paleoclimatological investigations, proxy data records are used from sources such as tree rings, glacial ice cores, pollen, lake and ocean sediments, and oxygen isotopes. These data are critical in providing long-term evidence by which climate conditions of the distant past can be evaluated. Often, climate reconstructions of meteorological variables such as air temperature, pressure, precipitation, and stream flow variability can be created from such sources.

Microclimatology

The localized study of unique climate conditions at or near the ground surface is another subdiscipline of climatology, known as microclimatology. This includes the assessment of vertical variations in climatological and meteorological conditions within 1 to 2 meters of Earth's surface. In addition, the horizontal variability of climate between site-specific locations is also examined in microclimatology. Important influences to the microclimate of a given area can include longwave and shortwave radiation flux, soil characteristics, topography, evapotranspiration rates, and the type and extent of vegetative cover. These elements are often highly variable between locations and between atmospheric layers located further from the surface layer. Microclimatology is closely connected to the study of larger-scale climate studies, as factors such as cloud cover and the movement of air masses and weather patterns may also affect the microclimate of an area. Of course, the nature of interactions between humans, animals, insects, and technology with the ground surface can also lead to unique and variable microclimate conditions. This field within climatology uses a host of monitoring systems, instrumentation (i.e., anemometers, hygrometers, thermometers, rain gauges, staff gauges, evaporimeters, and lysimeters), and sensors for observational measurements of climatological data.

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