Temperature
Temperature is a fundamental physical property of Matter that quantitatively expresses the common notions of hot and cold. It is a manifestation of the average Kinetic-Energy of the particles within a substance. The Laws-of-Thermodynamics govern how this energy is transferred between systems as Heat. In the International-System-of-Units, the base unit for measurement is the Kelvin, although Celsius and Fahrenheit remain widely used in Meteorology and daily applications.
Instruments such as the Thermometer are utilized to measure Temperature by observing physical changes, such as the expansion of a liquid or the variation in electrical resistance. The concept of Absolute-Zero marks the theoretical lower limit of the thermodynamic scale, representing a state where a system reaches its minimum possible Entropy. Scientific organizations like NIST and NASA provide extensive data on measurement standards and atmospheric conditions. For comprehensive scientific definitions, refer to Encyclopædia Britannica or the NIST Guide on Temperature.
In the realm of Statistical-Mechanics, Temperature is defined by the mathematical relationship between internal energy and the degree of disorder within a system. Understanding these interactions is vital for advanced fields like Cryogenics and Quantum-Physics. Furthermore, monitoring changes in global Temperature is a critical component of climate science, as detailed in reports by the IPCC (Source).