Everything ready to go outside, and a glance at the mobile tells us that it was 38 degrees outside.
Thinking that this is the temperature we are going to face when leaving home at five in the afternoon is an easy mistake to make.
The sidewalk or asphalt that is walked on at that time will radiate heat at more than 65 degrees.
The dashboard or bodywork of a dark vehicle parked in the sun will surely exceed 80 degrees (see methodology).
Knowing how heat behaves can be a matter of life and death, especially for workers who spend hours outside.
Or for children and the elderly, people who are more unprotected against excess body temperature, known as hyperthermia.
This is how heat works
25°
25°
Asphalt
Asphalt
The sun's rays pass through the air but do not heat it.
It is the surfaces that absorb solar energy and store it.
The ground radiates that accumulated heat and warms the air.
38°
65°
Asphalt
The heat emitted by the ground is greater near the surface, which makes children and pets more exposed.
38°
at 50cm
high the temperature can reach 50 degrees
Dogs can get burns on the pads
This is how heat works
25°
38°
25°
65°
Asphalt
Asphalt
Asphalt
The ground radiates that heat accumulated during the day and warms the air.
It is the surfaces that absorb solar energy and store it.
The sun's rays pass through the air but do not heat it.
38°
The heat emitted by the ground is greater near the surface, which makes children and pets more exposed.
at 50cm
high the temperature can reach 50 degrees
65°
Asphalt
Dogs can get burns on the pads
This is how heat works
25°
38°
25°
65°
Asphalt
Asphalt
Asphalt
The ground radiates that heat accumulated during the day and warms the air.
It is the surfaces that absorb solar energy and store it.
The sun's rays pass through the air but do not heat it.
38°
The heat emitted by the ground is greater near the surface, which makes children and pets more exposed.
at 50cm
high the temperature can reach 50 degrees
Asphalt
65°
Dogs can get burns on the pads
The heat does not come from above, it comes from below.
"The sun does not heat the air, the ground does," says Benito Fuentes, a meteorologist at the State Meteorological Agency (Aemet).
Atmospheric air is crossed by the sun's rays, a property called diathermy.
It is the surfaces that heat it.
The air is warmer near the ground or over surfaces that absorb a lot of heat, like plastic or asphalt.
And colder at higher altitudes, or above the sea or the grass.
A temperature measurement made during the last heat wave that Spain has suffered in a children's park in the capital shows very high figures on the metal, plastic and wooden surfaces of the attractions designed for children under 10 years of age.
The data collection was carried out when the thermometers marked 38 degrees, at the hottest time of the day, at five in the afternoon.
Playground
metal flooring
61°
38°
plastic slide
59°
Seat
rubber
66°
sand floor
37°
sand floor
50°
Temperatures measured during the second wave
of heat
July 17, 2022 at 5:00 p.m.
Playground
38°
plastic slide
metal flooring
59°
61°
Seat
rubber
66°
sand floor
sand floor
37°
50°
Temperatures measured during the second heat wave.
July 17, 2022 at 5:00 p.m.
Playground
38°
plastic slide
metal flooring
59°
Seat
rubber
61°
66°
sand floor
sand floor
37°
50°
Temperatures measured during the second heat wave.
July 17, 2022 at 5:00 p.m.
The danger of cars in the sun
The real danger is inside the cars.
A study led by University of California family medicine doctor Jennifer K. Vanos estimated that the body of a two-year-old locked in a car for an hour with an outside temperature of 41 degrees warms up to 39.7 .
It is a critical temperature for a child, which would cause death if continued exposure to heat.
The carelessness of parents who leave their children in the car causes 37 deaths in the United States each year.
The body temperature of a child
would rise 3 degrees in an hour
outside temperature
41.5°
indoor temperature
49.7°
Seat
56.1°
Steering wheel
60.6°
Dashboard
80.6°
39.7
A child locked in a car in the sun would experience an increase of up to three degrees in body temperature in one hour.
A greater confinement would cause death.
36.8
Temperatures measured from 13.10 to 14.10
on June 25, 2017
A child's body temperature would rise 3 degrees in an hour
outside temperature
41.5°
indoor temperature
39.7
A child locked in a car in the sun would experience an increase of up to three degrees in body temperature in one hour.
A greater confinement would cause death.
49.7°
Seat
56.1°
Steering wheel
60.6°
36.8
Dashboard
80.6°
Temperatures measured from 13.10 to 14.10 on June 25, 2017
outside temperature
41.5°
A child's body temperature would rise 3 degrees in an hour
indoor temperature
49.7°
Seat
56.1°
39.7
A child locked in a car in the sun would experience an increase of up to three degrees in body temperature in one hour.
A greater confinement would cause death.
Steering wheel
60.6°
Dashboard
80.6°
36.8
Temperatures measured from 13.10 to 14.10 on June 25, 2017
The determining factor of the study was the direct impact of the sun.
The authors also made measurements with the vehicle in the shade and the temperatures were much lower.
The air inside the car only increased by one degree.
A difference of more than 30 degrees was recorded on the dashboard and 15 degrees on the seats compared to the values measured in the sun.
El color de los vehículos influye además en la temperatura que puede alcanzar la carrocería y el habitáculo del coche. El investigador de la Aemet y doctor en física Juan Jesús González Alemán lo explica: “Los colores claros reflejan el calor, y eso es como una barrera para el sol. Estos colores limitan el calor que absorben los materiales”. Estas son las temperaturas que recogieron vehículos de diferentes colores en uno de los días más calurosos de la segunda ola de calor que ha azotado a España este julio.
Temperatura exterior
38°
55°
65°
80°
En las mismas condiciones el coche negro acumuló 25 grados más que uno blanco.
Temperaturas medida a las 17.00 en tres vehículos expuestos al sol durante todo el día.
Temperatura exterior
38°
55°
65°
80°
Temperaturas medida a las 17.00 en tres vehículos expuestos al sol durante todo el día.
En las mismas condiciones el coche negro acumuló 25 grados más que uno blanco.
Temperatura exterior
38°
55°
65°
80°
Temperaturas medida a las 17.00 en tres vehículos expuestos al sol durante todo el día.
En las mismas condiciones el coche negro acumuló 25 grados más que uno blanco.
Muertes relacionadas con el calor
Las situaciones extremas, como las de los niños en coches cerrados, no son las únicas que se deben evitar. El calor es el responsable directo o indirecto de cientos de muertes durante los meses de verano. La ola de calor dejó entre el 10 y el 18 de julio un balance de 863 fallecimientos atribuibles a la temperatura, según las estimaciones del panel de monitorización de la mortalidad diaria por todas las causas (MoMo) del Instituto Carlos III, un cálculo realizado a partir de las series históricas de mortalidad y de temperatura.
Defunciones atribuibles al exceso de temperatura
184
169
150
123
93
60
41
28
15
0
10
11
12
13
14
15
16
17
18
Segunda ola de calor
Julio 2022
Fuente: MoMo.
184
169
150
123
Defunciones atribuibles al exceso de temperatura
93
60
41
28
15
0
10
11
12
13
14
15
16
17
18
Segunda ola de calor
Julio 2022
Fuente: MoMo.
Aunque no todas estas muertes atribuibles a las altas temperaturas son debidas a los golpes de calor, dan una idea de la magnitud del problema y refuerzan la importancia de conocer cómo se comporta el calor y cuáles son sus efectos sobre el cuerpo humano.
¿Por qué las temperaturas máximas se registran por la tarde?
Pensar que las temperaturas máximas se dan al mediodía, cuando el sol está en lo más alto y los rayos son más intensos, es otra falsa creencia que puede llevar a elegir mal la hora a la que se realiza cierta actividad en el exterior. “El suelo tarda en absorber la radiación solar, no es un efecto inmediato”, indica el meteorólogo González Alemán, y continúa: “El calor máximo emitido por el suelo, que a su vez calienta el aire, se produce sobre las cuatro de la tarde, cuando el calor que expulsa es mayor que el que está ganando”.
Temperatura
maximum
Temperature
minimal
Solar energy
absorbed
on the floor
emitted energy
on the floor
0.00
4.00
8.00
12.00
16.00
20.00
0.00
Source: Meteorologist Juan Jesús González Alemán, via Twitter
Temperature
maximum
Temperature
minimal
Solar energy
absorbed
on the floor
emitted energy
on the floor
Midnight
4.00
8.00
12.00
16.00
20.00
0.00
Source: Meteorologist Juan Jesús González Alemán, via Twitter
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