Do you know why wet clothes dry up without heating and why we feel cool while sweating in the summer heat?

We know that heating water causes evaporation and the disappearance of water from the surface. However, have you also noticed that wet clothes dry even without giving any external heat and water spilled on the floor dries up on its own, given enough time? Let’s learn about the facts about evaporation that makes this possible.

First, let’s understand evaporation a bit more. As we know, the particles of a matter contain different amounts of kinetic energy. Solids have the least amount of kinetic energy, whereas gasses have the highest amount. Normally, the addition of heat is required to convert liquids to gasses. Liquids like water, however, can break free a little at a time from the surface due to the kinetic energy and convert into vapors. If this happens over time, all the liquid disappears and gets converted into vapors. This phenomenon is the one that we know as evaporation.
Factors affecting evaporation:
Evaporation depends upon various factors. All these factors increase or decrease the rate of evaporation in different ways:

1. Temperature: We know very well that as we increase the temperature, kinetic energy in the liquids would increase. This would result in the particles escaping the bounds of the liquid easily, and therefore, evaporation would happen easily.
2. Surface area: As we know, evaporation occurs on the surface. So, imagine what would happen if we increase the area of the surface. The amount of water getting evaporated at a time would increase, right? This is the reason why water inside a glass does not evaporate whereas when spilled on the floor, it evaporates so easily.

3. Humidity: Humidity is the quantity of water vapors present in the atmosphere. The air can only contain a fixed amount of maximum humidity. If the humidity in the air is already high, the evaporation does not happen as rapidly as when the humidity is low.

4. Wind speed: We see that using a fan to dry off a wet place is much faster than just letting it dry by itself. This is because the wind from the fan would remove the vapors from the immediate surroundings of the water. This results in a reduction in humidity and an increase in evaporation.

Evaporation causes cooling
As we know, particles gain energy from outside and convert them into kinetic energy to be used to change forms. Most of the time, this energy is the heat energy present in the surroundings. As they take away heat from the surroundings, the surrounding temperature decreases, and therefore, it causes the cooling effect. You can feel this when you put a drop of water on your hand or when your shirt gets wet with sweat in summer. In both of these cases, we can feel that cool sensation.
Since sweating is the body’s natural reaction to heat, we wear clothes that can absorb sweat and cool our body even more during summers. This is why it is advised to wear cotton clothes that have the property to absorb sweat and let air pass through its pores for easy evaporation.

Similarly, water droplets form on the outside of a water container that is holding cold water or ice. Water vapors present in the surrounding environment come into contact with the container and lose their energy, resulting in particles coming closer. This results in their condensation and forming droplets on the container.

So, here we saw that evaporation is controlled by multiple factors and causes the cooling of the surrounding atmosphere.

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