Thermometry is basically the process of measuring the temperature of a particular material or substance, often through the use of an arbitrary but commonly agreed upon scale. The temperature of an object is typically viewed with regard to energy in that object, usually heat release or absorption. There are a number of different ways in which this type of temperature can be measured, though common methods include contact and noncontact measuring procedures. Thermometry measurements can be expressed using a number of different systems such as Fahrenheit (F), Celsius (C), and Kelvin (K) that typically refer to different units in terms of numerical degrees.
The general purpose of thermometry is to measure the temperature of an object, which can be a solid, liquid, or gas. Temperature is a basic expression with regard to how “hot” or “cold” an object is, which indicates whether heat is likely to be transferred to it by another object or from it to that object. The temperature of an object is based on the kinetic energy of particles within that object, and is an expression of energy being released or absorbed by it. Thermometry can be used to measure the temperature of an object to provide information for that material with regard to other objects in a quantitative way.
There are several different ways in which measurements can be taken in thermometry, though most techniques fall into either contact or noncontact methods. Contact measurements are taken by bringing one object in direct contact with another, which matches the temperature of the second object, and then relays information about temperature. A common glass thermometer, for example, uses this type of measurement as the mercury within the glass matches the temperature of a person and expands based upon that new temperature. Noncontact measurements in thermometry do not require physical contact between two objects and can include the use of infrared thermometers to measure temperature based on heat emission from an object.
Different scales have also been developed for measurements made in thermometry, and the preferred scale is often dependent upon the context in which is it used. Most scales for thermometry utilize degrees or “°” as the unit for measurement, though the Kelvin scale, often used in scientific measurements, does not. In the US, the most common scale for non-scientific measurements is Fahrenheit, in which water freezes at 32° F; and boils at 212° F;. Celsius is used in many other countries, such as the UK, and was previously known as “Centigrade;” water freezes at 0° C and boils at 100° C.