Atualizado: 28 de set. de 2022
Climate change has crept on us and causes worldwide disasters while showing our vulnerability to health issues. Coupled to higher pollution levels one concept that has affected people is living in a vacuum city.
Living in a vacuum city like São Paulo, Brazil, means the air temperature can change drastically from midnight to midday while dropping once again as the day ends. For many citizens the body cannot cope which ends up in creating respiratory disorders, especially during the winter months of the year.
For instance, this causes the atmospheric temperature to decrease in height. Sometimes, the opposite happens: the bottom of the valleys registers colder temperatures than the summits of the mountains. This phenomenon is a consequence of the thermal inversion or inversion of temperature.
Thermal Inversion occurs worse in the middle of the night during the winter months and is more likely in the south of the country. In the north of Brazil where the weather remains positively tropical with days averaging between the mid-20s to low 30°C (68 to 86°F) very occasionally, if at all. In the south, when the winter strikes from May to September the risk of thermal inversion is very real.
Under normal conditions it is fine, as during the day, the sun heats the Earth’s surface, which releases the heat little by little, heating the air from the adjacent atmosphere. This warmer air has a lower density, that is, it weighs less, which facilitates its ascent through the different layers that form the Earth’s atmosphere (the rise of a hot air balloon exemplifies this phenomenon very clearly).
As it rises, the hot air cools and acquires greater density or weight, which causes gravity to attract it more strongly and displace the hot air closer to the Earth, generating a convective movement. However, during the long cold winter nights and in conditions of atmospheric stability such as those presented by the anticyclones (clear skies, little wind, etc.), this normal operation tends to break down.
According to my research thermal inversion is a natural phenomenon that involves a change in the normal tendency of the air to cool down with altitude. During the night, the earth’s surface cools quickly, transmitting that cold to the atmosphere closest to the ground. This layer of air has a lower temperature than the immediately higher one, that is, both have different densities, which prevents mixing.
Having had asthma on and off during my life has been a burden. Moreover, since living in São Paulo it has become apparent that the changing weather (more so in the winter) has been detrimental to my respiratory system, and as a consequence many yearly spells have been spent recovering from breathing disorders. I’ve noticed a period at night when breathing is difficult and pollution is high. I’m talking from about 2am to 4am when the air is stale and it upsets my breathing tract.
In a nutshell, the warmer air rises and acts as a lid trapping the colder air close to the ground. Pollution, including that from road traffic is also trapped, so the air layer closest to the ground becomes more and more polluted.
Prof. Carl Boniface
Crept (v) past of to creep i.e., tiptoe, sneak, crawl, slither
Convective movement (n) = the action or process of conveying. Or movement in a gas or liquid in which the warmer parts move up and the cooler parts move down convection currents.
Spells (n) = bout, period, interludes, stretches, sessions. Also known as enchantments, magic, evil eye
Stale (adj) = decayed, sour, old, musty, hard, out-of-date, past its sell-by date, gone off, past its best, out of date, (ant) fresh
In a nutshell (idiom) = to sum up, in a few words, when all is said and done, in summary, to cut a long story short, all things considered