Temperature
 

To measure temperature, heat or infrared waves must be transferred to a probe. Heat causes a change in the volume of a liquid, resistance of a thermistor or resistance in a doped semiconductor pickup cell (for infrared). All heat transfers take time and must conduct material boundaries. Since heat transfer takes time, temperature measurement is always delayed. Insulation and mass is used to increase the amount of time delay and provide for an average temperature. Thermistors take less time for heat transfer and infrared thermometers are the fastest at reading temperature. Accuracy of the reading depends upon the transfer of energy and the thermometer's ability to measure the energy. The freezing point is 0° C, 32° F, with pure ice water at sea level. The boiling point is 212° F, 100° C, in pure water at sea level. The boiling point in this area is approximately 209.5° F for pure water. Electrolytes and other materials dissolved in water raise the boiling point and lower the freezing point. The Environmental Protection Agency (EPA) recommends that temperature be read and recorded at + or - 0.1° C
 
 
 

Temperature and Random Energy

A thermometer measures the average random energy. This measurement is called temperature.  Temperature can be averaged over different time intervals by using insulation or the conductivity of the material surrounding the sensor. Sensor fluid (like mercury) expands as the temperature increases.  Thermistors, which are electrical temperature probes, increase activity and change resistance as temperature increases. Any material that has mass possesses random energy. The term random is used because the molecules, which are constantly moving, collide with other molecules and energy is transferred. The energy transfer provides the means for some molecules to break apart(cracking in petroleum, ionization in water, viscosity change from heat in an engine) or escape from the material's
surface. The numbers of molecules that break free are dependent upon the energy contained within the specific material. The more energy that is transferred between the molecules, the more energy variance in molecular action occurs. Thus temperature is a measure of the average random energy of the motion
of molecules. This example visualizes the imparting of energy to another molecule.


In the randomness of any sample, some motion is orderly. This sometimes-orderly alignment of molecules in motion allows the transfer of random energy to impart enough energy in a specific direction to one molecule allowing it to escape the forces of surface tension. An important concept to
remember it that nature dilutes and man concentrates. Random energy in molecules causes some of this dilution. Nature also uses other forms of energy to dilute. In nature, all things are random to some order of magnitude. For example, random energy causes salt to be in the air above the oceans.  Moisture condenses on the salt particles helping to produce rain and regulate the amount of salt
molecules in the atmosphere.