# Thermal phenomena - they are around us

Education

The source of energy for the Earth is the Sun.Solar energy is the basis of many phenomena occurring on the surface and in the atmosphere of the planet. Heating, cooling, evaporation, boiling, condensation are some examples of what thermal phenomena occur around us.

No processes in themselves occur.Each of them has its source and implementation mechanism. Any thermal phenomena in nature are due to the receipt of heat from external sources. This source can act not only the Sun - the fire also successfully copes with this role.

To further understand what isrepresent thermal phenomena, it is necessary to define heat. Heat is the energy characteristic of heat exchange, in other words, how much energy is given to the body or system by interaction. Quantitatively it can be characterized by temperature: the higher it is, the more warmth (energy) this body possesses.

In the process of interaction of bodies with each otherthere is a transfer of heat from hot to cold body, i.e. from a body with a higher energy to a body with a lower energy. This process is called heat transfer. As an example, you can consider boiling water poured into a glass. After a while, the glass will become hot, i.e., there was a process of transferring heat from hot water to a cold glass.

However, thermal phenomena are not only characterizedheat transfer, but also such a concept as thermal conductivity. What it means can be explained by an example. If you put the frying pan on the fire, then its handle, although it does not come into contact with the fire, will heat up just like the rest of the frying pan. Such heating is provided by thermal conductivity. Heating is carried out in one place, and then the entire body is heated. Or it does not heat up - it depends on what kind of heat conductivity it has. If the thermal conductivity of the body is high, the heat is easily transferred from one area to another, if the thermal conductivity is low, then heat transfer does not occur.

Before the concept of heat, the physics of thermalphenomena explained with the help of the concept of "heat". It was believed that each substance has a certain substance, analogous to a liquid that performs the task, which in the modern view is decided by heat. But the idea of ​​heat was abandoned after the concept of heat was formulated.

Now it is possible to consider in more detailpractical application of previously introduced definitions. Thus, thermal conductivity provides heat exchange between bodies and within the material itself. High values ​​of thermal conductivity are inherent in metals. For dishes, a teapot is good, because it allows you to supply heat to the cooking products. However, materials with low thermal conductivity also find their application. They act as heat insulators, preventing heat loss - for example, during construction. Due to the use of materials with low thermal conductivity, comfortable living conditions in houses are provided.

However, the above heat transfer methodsnot limited. There is also the possibility of transferring heat without direct contact of bodies. As an example - the flow of warm air from the heater or radiator of the heating system in the apartment. From the heated object (heater, radiator), a warm air stream emanates, heating the room. A similar way of exchanging heat is called convection. In this case, heat transfer is carried out by liquid or gas flows.

If we recall that thermal phenomena,occurring on the Earth, are associated with the radiation of the Sun, then there is another way of heat transfer - thermal radiation. It is caused by the electromagnetic radiation of the heated body. This is how the Sun heats the Earth.

In the above material, variousthermal phenomena, describes the source of their occurrence and the mechanisms by which they occur. The questions of practical use of thermal phenomena in everyday practice are considered.