基于桃中的同位素的前坎布里亚海洋的古气温曲线
François Robert1, Marc Chaussidon
1Muséum National d'Histoire Naturelle, CNRS LEME NanoAnalyses, UMS 2679, 57 rue Cuvier, 75005 Paris, France. robert@mnhn.fr
Nature
|October 27, 2006
概括
根据对古代桃的同位素分析,甲纪前的海洋显著降温,从70°C降温到20°C. 这种新方法证实了长期的海洋冷却趋势,解决了关于气候数据可靠性的以前的辩论.
科学领域:
- 地质化学 地质化学
- 古气候学 古气候学
- 沉积地质学的地质学
背景情况:
- 前坎布里亚时期的气候记录显示了极端的温度波动,从极端的高温到全球的冰川.
- 桃中的氧同位素比率已被用来推断过去的海面温度,但由于潜在的沉积后变化,它们的可靠性受到争议.
相关概念视频
Heating and Cooling Curves
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
Thermometers and Temperature Scales
Any physical property that depends consistently and reproducibly on temperature can be used as the basis of a thermometer. For example, volume increases with temperature for most substances. This property is the basis for the common alcohol thermometer and the original mercury thermometers. Other properties used to measure temperature include electrical resistance, color, and the emission of infrared radiation.
As many physical properties depend on temperature, the variety of thermometers is...
As many physical properties depend on temperature, the variety of thermometers is...
Gas Thermometers and the Kelvin Scale
The definition of temperature in terms of molecular motion suggests that there should be a lowest possible temperature, where the average kinetic energy of molecules is zero (or the minimum allowed by quantum mechanics). Experiments confirm the existence of such a temperature, called absolute zero. An absolute temperature scale is one whose zero point is absolute zero. Such scales are convenient in science because several physical quantities, such as the volume of an ideal gas, are directly...
Isothermal Processes
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to maintain thermal equilibrium. Processes involving phase changes like water evaporation into steam or freezing water into ice at a constant temperature are examples of Isothermal Processes.
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
The Clausius–Clapeyron Equation
The Clausius-Clapeyron equation is a fundamental principle in physical chemistry and thermodynamics that describes the relationship between a substance's vapor pressure and temperature. Named after Rudolf Clausius and Benoît Paul Émile Clapeyron, the equation is integral in predicting a substance's behavior under different temperature conditions.The Clausius-Clapeyron equation allows us to calculate how the pressure at which a liquid boils (its vapor pressure) changes as the temperature changes.
Energy Line and Hydraulic Gradient Line
Based on Bernoulli's equation, the energy line (EL) and hydraulic grade line (HGL) provide graphical representations of energy distribution in a fluid flow system. For steady, incompressible, inviscid flows, Bernoulli's equation is expressed as:


