Phenomenon that always result in cooling effect:

There are several phenomena that result in cooling effects. However, the following two phenomena always result in cooling effects:

1. Evaporation:

Evaporation is the process of converting a liquid into a gas. It always results in a cooling effect because the molecules with the highest kinetic energy escape from the surface of the liquid, leaving behind molecules with lower kinetic energy. This causes a decrease in the average kinetic energy of the remaining molecules, which results in a decrease in temperature.

For example, when sweat evaporates from the surface of our skin, it cools our body because the heat energy required for evaporation is taken from our skin, which lowers the skin's temperature.

2. Expansion:

Expansion is the process of increasing the volume of a substance. This process always results in a cooling effect because the molecules of the substance move further apart from each other, which results in a decrease in temperature.

For example, when a gas is allowed to expand rapidly, such as when a compressed air canister is opened, the gas cools because the molecules move further apart from each other, which results in a decrease in temperature.

Conclusion:

In conclusion, both evaporation and expansion always result in cooling effects. Understanding these phenomena is important in many areas of science and technology, including air conditioning, refrigeration, and climate science.