What's the feeling of MINUS 40 degrees?

Temperature is a physical quantity that indicates the degree of heat and cold of an object, and it is the intensity of molecular thermal motion of the object at the microscopic level. Temperature can only be measured indirectly through some characteristics of an object that changes with temperature. The scale used to measure the temperature value of an object is called a temperature scale.

It specifies the reading starting point (zero point) of temperature and the basic unit for measuring temperature. The international unit is the thermodynamic temperature scale (K). Other temperature scales widely used in the world are Fahrenheit scale (F), centigrade scale scale (C) and international practical temperature scale.

From the perspective of molecular motion theory, temperature is a sign of the average kinetic energy of an object's molecular motion. Temperature is the collective expression of a large number of molecular thermal movements, which has statistical significance. For a single molecule, temperature is meaningless. According to an observable phenomenon (such as the expansion of mercury column), the degree of heat and cold is measured by one of several arbitrary scales.