How to keep cool this summer using physics

The Summer Season in the UK, US and most parts of Europe covers the months of June, July and August. It is the warmest season of the year marked with longer days and shorter nights. The days are usually very sunny, hot, humid and dry with average daily temperatures around 20 (Degrees) Centigrade. In severe cases, it rises to even as high as 32 (Degrees)  Centigrade leading to Heat waves. 

While the Summer heat can reach scorching levels, the season also affords a get-away from the characteristic incapacitating cold in these regions. Which is why people plan their holidays this period. 

For the purpose of our discussion, the most relevant characteristic of this season is heat.

Heat

This is defined as a form of energy which is as result of temperature difference between two bodies or points. It is measured in Joules (J). Temperature is the degree of hotness or coldness of a body and is measured in Degree Centigrade (C) or Fahrenheit (F). Heat is usually transferred from a region of higher temperature (the Sun, in this case) to region of lower temperature (Earth, in this case).

During the Summer season, the Earth tilts closer to the sun making the rays to hit earth at a steep angle. As result, there is less dissipation of the heat at any given point. Also, the longer daylight leads earth to acquire heat for longer. These two reasons account for the severe temperature encountered in the sesason.

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Heat Transfer

Heat is tranferred via 3 major ways:

1. Conduction: this is heat transfer in a solid by direct contact. This is made possible by movement of energised molecules (Kinetic Energy) when heat is applied.

2. Convection: this is heat transfer in fluid due to movement of the molecules of the fluid as result of heat application. The energised molecules move upward while the less energised ones move downward. The process continues until equilibrium. E.g Boiling water

3. Radiation: this is heat transfer via the movement of electromagnet waves. This does not require a material medium and can travel through space. E.g the heat from the Sun reaches us via radiation, the heating of a room by an open hearth fireplace.

When heat falls on a surface, it is absorbed, transmitted or reflected depending on the material it falls on. This is why the internal temperature or enthalpy increases, reduces or remains the same.

Black bodies theoretically absorbs all the heat incident on them while white reflects the heat incident on it. The ability of a body to conduct heat is known as its thermal conductivity and this property can be helpful in deciding materials to use when heat transfer is concerned. Other important property to consider is thermal reflectivity.

How to keep cool this summer

So far we have discussed a basic feature of summer, heat and we have looked at definitions of some key terms. Let us see how we can apply some of the knowledge to keep cool this summer.

1. What we wear and How We Dress: dark coloured clothing have been established to be good radiators or absorbers of heat. While light coloured ones reflect heat and absorb little amount of heat. This is why most summer wears are designed to be in lighter colours. So the summer season should favour more lighter clothing.

Also, the material properties of the clothing counts. Wool, Linen and Cotton are designed to dissipate heat, air and moisture and thus feel cooler to wear than silk and polyester fabrics. Then also, we should wear clothing that are light as this will not create a drag that will lead to more work and heat generation from our bodies.

Other items we can use are hats, umbrellas, etc designed in light colours.

This principle also applies to our cars and homes. The darker their colours the more heat they will absorb.

2. Create Shade: some of our houses are blessed with abundance of trees and vegetation to provide shade and protect from the heat of the Sun and provide sufficient air. Additionally, we can create shade by using materials with high reflectivity index. This can help reduce thermal absorption via roofs, windows and other openings. Other suitable alternatives are white or bright coloured paints, aluminium foil, reflective films, low emissivity coatings on glass, curtains, blinds, etc

3. Use of Convection for Cooling: this will be to increase airflow in our homes, workplaces, schools, etc by use of fans, opening of windows to let in more air. As cooler air enters, the hotter air rises and is replaced gradually.

4. Make Water Your Close Friend: due to increase in sweat water leaves our bodies and by drinking water frequently, we keep hydrated and healthy. Also, frequent cool showers can help in lowering body temperature.

5. Evaporative Cooling: evaporation is the change of state from liquid to vapour. For this to happen, it needs heat energy from the surrounding. This heat energy is called latent heat. As the heat is taken from the surrounding by the liquid, the surrounding feels cool due to drop in enthalpy. Example is when methylated spirit touches our skin, we immediately feel cool as the liquid evaporates.

We can use this principle by use of misting fans, evaporative coolers, swamp coolers, use of wet clothes in front of a fan, leaving the bathroom doors open and so on.

6. Use of Air Conditioning Systems: this system uses similar principle as the evaporative cooling as the refrigerant uses the ambient heat to change from solid to liquid through the process of melting. By taking the heat it needs away from the rooms, the room temperature drops while the external temperature of the air conditioning system outside increases. We can feel the hotness when we touch the part of the air conditioning system just outside our rooms.

Conclusion

Life is about creating solutions to problems. Whether it be summer or winter, we would always be faced with weather extremities and even more considering that we continue to offset the dynamics of the ecosystem by our activities. It is thus important that we continue to use and apply the knowledge and principles we acquire in physics, chemistry and science in general to make better and informed choices in our every day living.

Please note that the ways suggested here are not exhaustive. There are other ways such as design considerations for our homes, eating lighter foods during the day to reduce internal combustion in our systems, avoiding alcohol and so on. The beauty of science is that it is constantly evolving around some basic principles. How we apply these principles is what counts in our every day living.