TEMPERATURE. Hot and Cold.

TEMPERATURE. Hot and Cold.

Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is colder or hotter.

Temperature, measure of hotness or coldness expressed in terms of any of several arbitrary scales and indicating the direction in which heat energy will spontaneously flow—i.e., from a hotter body (one at a higher temperature) to a colder body (one at a lower temperature). Temperature is not the equivalent of the energy of a thermodynamic system; e.g., a burning match is at a much higher temperature than an iceberg, but the total heat energy contained in an iceberg is much greater than the energy contained in a match. Temperature, similar to pressure or density, is called an intensive property—one that is independent of the quantity of matter being considered—as distinguished from extensive properties, such as mass or volume.

Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have used various reference points and thermometric substances for definition. The most common scales are the Celsius scale (formerly called centigrade, denoted as °C), the Fahrenheit scale (denoted as °F), and the Kelvin scale (denoted as K), the last of which is predominantly used for scientific purposes by conventions of the International System of Units (SI).

We can use our fingers, our tongue, or almost any part of our skin to feel just how hot or how cold something is. This is important because our bodies need just the right amount of heat so that we can live comfortably.

When it's cold and we want to make a room warmer, we turn on the heater. In the summer when it's hot and we want to make the room cooler, do we add cold to the room?

No. We take away some of the heat. We say something is cold when it doesn't have much heat. The less heat it has, the colder it is.

TEMPERATURE. Hot and Cold.

Air conditioners suck hot air from a room. Pipes inside the air conditioners take a lot of heat out of the air, making it cold. Then a blower fans the cooled air into the room again.

When we want to know exactly how hot or how cold something is, we use a thermometer. A thermometer tells us about temperature - that is, how hot something is. Some countries measure temperature in 'degrees Celsius (°C)'. Others use a different measuring system of 'degrees Fahrenheit (°F)'.

We can use thermometers to measure air temperature, oven temperature, even body temperature. And your body temperature tells not only whether you feel hot or cold but whether you're healthy.