Temperature Converter

-40° is the unique temperature at which Celsius and Fahrenheit scales are equal (-40°C = -40°F).

Kelvin is an absolute temperature scale, meaning 0 K (zero Kelvin) is absolute zero, the theoretical lowest possible temperature where all atomic motion would cease. This corresponds to -273.15°C or -459.67°F.

Early thermometers used various substances like alcohol or mercury. Fahrenheit based his scale on three fixed points: a brine solution's freezing point (0°F), water's freezing point (32°F), and human body temperature (originally set at 96°F, later adjusted).

The surface temperature of the Sun is about 5,500°C (or about 9,940°F). The core, however, is immensely hotter, estimated at 15 million °C (27 million °F).

Humans are warm-blooded, maintaining a constant internal body temperature of around 37°C (98.6°F). This process, called thermoregulation, involves mechanisms like shivering (to generate heat) and sweating (to lose heat).

The Mpemba effect is the observation that, under certain circumstances, hot water can freeze faster than cold water. While counter-intuitive, it's a real phenomenon whose exact cause is still debated by physicists.

The lowest natural temperature ever directly recorded at ground level on Earth is −89.2 °C (−128.6 °F) at the Soviet Vostok Station in Antarctica on 21 July 1983.

The Rankine scale is another absolute temperature scale that uses Fahrenheit degrees instead of Celsius. Absolute zero is 0°R, which is -459.67°F. It's sometimes used in engineering contexts in the United States.

Heat is a form of energy that flows from a hotter object to a colder one. Temperature is a measure of the average kinetic energy of the atoms or molecules in a system. A spark from a fire has a very high temperature, but contains very little heat energy.

All objects with a temperature above absolute zero emit thermal radiation. At room temperature, this is mostly in the infrared spectrum, which is invisible to the human eye but can be detected by thermal cameras.

At higher altitudes, atmospheric pressure is lower, which causes water to boil at a lower temperature. For example, in Denver, Colorado (at 1600m), water boils at about 94°C instead of 100°C.

Superconductivity is a phenomenon where certain materials exhibit zero electrical resistance when cooled below a critical temperature. This temperature is often very low, typically measured in Kelvin.

The universe is filled with faint microwave radiation, a remnant of the Big Bang. This Cosmic Microwave Background has a uniform temperature of about 2.725 Kelvin, just a few degrees above absolute zero.

The Réaumur scale was another historical temperature scale where water froze at 0°R and boiled at 80°R. It was used in parts of Europe but is now largely obsolete.

Used in the early 20th century for low-temperature physics, the Leiden scale had its zero point at the boiling point of helium, which was a convenient reference for cryogenics labs at the time.

Plasma, the fourth state of matter, can reach incredibly high temperatures. The plasma in a fusion reactor, like a tokamak, can reach over 100 million Kelvin, far hotter than the core of the sun.

In some specific quantum systems, it's possible to achieve a state described by a negative Kelvin temperature. Paradoxically, these systems are infinitely hot, not cold. They have more particles in high-energy states than in low-energy states, the reverse of normal matter.

A thermocouple is a temperature sensor made of two different types of metal wires joined at one end. A temperature difference between the joined end and the other end creates a small voltage, which can be measured to determine the temperature. They are used for very high temperature measurements.