Evaporation is key in the water cycle.
Evaporation is the action and effect of evaporating or evaporating . This verb, for its part, refers to the transformation of a liquid into vapor .
During the physical process called evaporation - a term from the Latin evaporatio -, a liquid substance slowly and gradually passes into a gaseous state, once it has acquired the energy necessary to increase its surface area . It is important not to confuse this term with boiling , since evaporation does not require a particular temperature ; Furthermore, the larger it is, the sooner it will take place.
It is worth mentioning that this is an absolutely necessary phenomenon for the cycle of life , given that water in a gaseous state condenses and becomes clouds, which regain their liquid form during rain , which keeps our soils fertile. Likewise, this return of water to the earth can occur through snowfall, dew or fog.
Evaporation development
On the surface of a liquid substance, unless there is some obstruction, a portion of its molecules is in a gaseous state. When this balances, the pressure of the saturating gas phase is established, which is not directly related to the volume, but to the temperature and type of liquid. If the amount of gas is less than said pressure, then evaporation takes place, since a percentage of the molecules change state ; On the other hand, if the pressure is equal to that of the atmosphere, boiling occurs.
When very few molecules are close to the surface and performing a correctly directed movement to escape from the liquid at some point, the evaporation percentage is limited. Furthermore, given that those that manage to escape are those that have more energy than the rest, the substance suffers a considerable reduction in temperature (this is called evaporative cooling , and takes place during the phenomenon of sweating).
Evaporation of sweat helps remove heat from the body.
sweat
With respect to sweat , it should be noted that during its evaporation more than twenty percent of the heat is removed from our body, given that water has a particularly high specific heat and the energy it requires to evaporate remains from our body, making it its temperature decreases. More specifically, 0.58 kcal are needed to eliminate 1 g of sweat; These are obtained from the skin, which causes it to cool and eventually affects body temperature. When a current of dry air replaces humid air, an increase in evaporation is seen.
It is possible to distinguish between insensible evaporation , which occurs through our skin tissue (when the humidity of the air does not reach 100 percent) and through the nasal passages, and superficial evaporation , which comes from the sweat glands, which exist in many parts of our body, but especially in the inguinal area, the armpits, the forehead and the palms of the hands and feet.
Other Evaporation Considerations
If evaporation takes place in a closed container, those molecules that manage to escape from the liquid group in a gaseous state on top of it and many of them return to their liquid form. When this back-and-forth process reaches an equilibrium (called evaporative ), there are no more transformations in the pressure of the vapor (which in this case is called saturated ) or in the temperature of the substance.
For hydrology , a natural science that studies water, evaporation is considered a very significant variable when seeking to calculate the water balance (the relationship between the input and output of water resources during a specific period of time) of hydrographic basins, be it total or partial, taking into account its surface of origin.