What really happened?

These last days, A powerful heat wave coming from the vast steppe expanses of the Chaco has affected much of South America. Specifically the southern states of Brazil, where the exceptional heat coming from the interior regions of South America is mixed with the very high levels of relative humidity that characterize these places.

This combination of very high relative humidity and very hot air coming from remote areas made it possible to reach terrifying “heat index” values.. However, it should be noted that data on actual air temperature should not be confused with those on “heat index” values. It is calculated by indicating the relationship between relative humidity and air temperature.

Exceptional heat in the Rio de Janeiro metropolitan area

last sunday, In the Rio de Janeiro metropolitan area, very high maximum temperatures were measured, reaching 38 to 40 degrees Celsius in the shade or under shelter.. Even the lowest temperatures, in the middle of the night, did not fall below 30 degrees Celsius, making the atmosphere unbreathable, precisely because of the extremely high relative humidity levels.

This adds to a feeling that has been very strong in the Rio de Janeiro area, leading to sleepless nights for millions of Brazilians. The presence of such high values ​​of relative humidity is mainly due to the city's exposure to the ocean and dense tropical vegetation.Located along the hills surrounding downtown Rio, they are capable of releasing large amounts of water vapor into the atmosphere, especially at night.

I felt a temperature of 62.3

This mixture ranges between temperatures ranging from 38 to 40 degrees Celsius and very high relative humidity valuesOften greater than 50 or even 60%, It led to the recording of the felt temperature values, also called the heat index, at 62.3. This is the highest value recorded since the first meteorological measurements began in the region.

The previous record was set last November when the heat index reached 59.7. Also on Sunday, the temperature was measured in the state of Mato Grosso, 39 degrees Celsius in Corumba. In the state of Paraná, in Paranapuima, the maximum temperature reached 38 degrees Celsius. The same value registered in Rio Grande do Sul, in the cities of Alegrete and Santa Cruz.

The extremely stifling heat is set to continue for a few more daysTaking into account the appearance of a cold front coming from southern Brazil, followed by cold air of temperate oceanic origin, which, when colliding with the pre-existing very hot and humid climate, will give rise to violent periods of time. By the end of this week, some of these storms will also affect the Rio region de Janeiro, putting an end to the oppressive heat wave witnessed in recent days.

Be careful not to confuse the temperature you feel with the real temperature.

Regarding the 62.3 recorded last Sunday in the Rio de Janeiro area, we must be very careful Do not confuse data about the real temperature with the “felt” temperature value..

In the case of 62.3, this is the “felt” temperature and not the actual temperature. This means a value, or rather an index, of thermal discomfort calculated on the basis of the relationship between real temperature and humidity. If high humidity levels are combined with high temperatures, the indicators of thermal discomfort increase.

In this case, Humidity plays an essential roleBecause when this increases, in conjunction with very high air temperatures, the perception of our body heat increases significantly compared to reality.

” We don't need to chase sensationalist information or data to prove that climate change already exists and we can see the consequences.. In this case, Brazil is experiencing a strong heat wave ranging between 37, 38 and even 40 degrees Celsius locally. However, perceived temperature is an incorrect term, and perception is subjective and depends on various factors. More precisely, it is called the “heat index”, and in any case this value leaves me very puzzled,” explains Luca Lombroso, meteorologist from Meteored.

To give a trivial example, a temperature of 37°C with a relative humidity of 80% constitutes a heat index of about 60Which represents a serious danger to our health, especially for the elderly who are vulnerable to serious diseases. It's like what happened a few days ago in the Rio de Janeiro area.