Скачать или смотреть Balloon Thermodynamics: Rapid Expansion

Rapid expansion causes cooling because of the relationship between temperature, pressure, and volume in a gas. According to the ideal gas law (PV=nRT), the pressure of a gas is inversely proportional to its volume at constant temperature. This means that as the volume of a gas increases, its pressure decreases.

When a gas rapidly expands, it does work on its surroundings, which increases the internal energy of the surroundings but decreases the internal energy of the gas. Since temperature is a measure of the internal energy of a substance, this decrease in internal energy results in a decrease in temperature of the gas. This is why a gas that rapidly expands will cool down.

This effect can be seen in many everyday examples, such as the cool mist produced by an aerosol can or the cool air expelled by a refrigerator's compressor. The pressurized gas inside the can or compressor is rapidly expanding as it is released, and this rapid expansion causes the gas to cool down.

Another example, When an air-conditioner, the refrigerant is compressed and heated, and then it is rapidly expanded into a low-pressure area. This rapid expansion causes the refrigerant to cool down significantly. This cooled refrigerant is then circulated through a system of coils, where it cools and dehumidifies the air inside the room.

Rapid expansion also occurs in nature, such as in thunderstorms where lightning rapidly heats and expands the air, creating the characteristic thunder sound and causing the air to cool rapidly.

It is important to note that the cooling effect from the rapid expansion is dependent on the internal energy of the gas and it may not be the case for some real gases.