Temperatur

Temperatur is the German term for temperature, a physical quantity describing how hot or cold a system is. In physics it measures the average kinetic energy of particles and is a fundamental state variable that, with pressure and volume, characterizes a system. Temperature also governs the direction of heat flow: heat moves from hotter to cooler bodies until they reach thermal equilibrium.

Temperature is measured with thermometers and reported on several scales. The common ones are Celsius (°C), Kelvin (K), and Fahrenheit (°F). Water freezes at 0°C (273.15 K) and boils at 100°C (373.15 K) at one atmosphere. Kelvin is the absolute scale, starting at absolute zero (-273.15°C), and is favored in scientific work.

Principles of thermodynamics define temperature operationally. The Zeroth Law states that if two systems are each in thermal contact with a third, they are in thermal equilibrium with each other. Temperature changes reflect heat transfer and changes in internal energy, while the second law introduces entropy and limits on energy conversion.

Thermometers range from liquid-in-glass devices to electronic sensors, including thermocouples and resistance thermometers. Selection depends on range, response time, and environment. Accurate measurement requires proper calibration, appropriate immersion, and consideration of ambient conditions.

In science and daily life, temperature affects phase transitions, reaction rates, material properties, climate, and weather. It is an intensive property: its value does not depend on the amount of substance present, enabling meaningful comparisons and the analysis of thermal processes.