Our Dynamic Planet: Earth And Life, Glossary

S279 Our dynamic planet: Earth and life Glossary for Book 2 acritarch Any small non-calcareous, nonsiliceous organic structure that cannot otherwise be classified. adiabatic From the Greek for ‘impassable’ – a reference to the fact that heat passes neither from or to a substance undergoing an adiabatic process. advection Transfer of heat by physically moving material. albedo The fraction of incoming solar radiation that is reflected from a surface. anoxic Without oxygen, or oxygen poor. aphelion The point on an orbit which lies furthest from the Sun. atmospheric window The range of longwave radiation leaving the Earth system between 8–13 µm where there is relatively little absorption. autotrophic Organisms that manufacture their own food. bacteria Very small, single-celled life forms: the most primitive living beings. bicarbonate ion (HCO3–) biogeochemical cycle Global cycling of an element used by organisms. biological pump The transfer of carbon from surface waters to the deep ocean. biolimiting Nutrients that can become completely used up by phytoplankton, thus preventing the growth of further organisms. biomes Distinct ecosystem types. biota All the plant and animal life of a region. boundary layer The relatively still and humid layer of air next to the ground. Cambrian Explosion The diversification of modern bilaterian life at the beginning of the Phanerozoic. carbohydrates Sugars, starches, and cellulose, which contain C, H and O forming chains of simple sugars and which function primarily in energy storage, energy transport, and plant structure. carbonate compensation depth, CCD The depth in the ocean at which the proportion of calcium carbonate remaining falls to less than 20% of the total sediment. carbonate ion (CO32–). carbonate platforms plateaux. Broad, shallow, submarine carbonate system The reactions th