On hot summer days it can feel stuffy and it seems like it is much warmer than the thermometer indicates.
This has to do with the combination of temperature and humidity. Where the wind chill is used for cold/frost,
taking into account the ambient temperature and wind speed, the Heat index is therefore used for the heat.
The combination of warm and moist air makes us experience the heat more extreme than it actually is.
The temperature that our body experiences (actually the heat wind chill) is indicated by the
heat index (also known as heat index (HI), Humiture and Humidex).
If the temperature is above 30 degrees Celsius, the human body has trouble losing its heat and
this only succeeds through perspiration, which evaporates and thus extracts heat from the body.
If the humidity is very high, however, our sweat will evaporate less well, so that the heat can be
extracted less well from our body and the heat therefore remains in our body.
If we are physically very active in that kind of weather (high temperature + high humidity),
for example work or sport, there is a danger of overheating of the body. This can have fatal consequences,
especially for the elderly and people in poor health. The KNMI uses a table for the Heat Index
(developed by Robert Steadman, also known for the wind chill / wind chill). The heat index is based
on little wind and shady surroundings. In the sun, the heat index can be up to 10 degrees Celsius higher.
With a heat index between 25 and 30 degrees Celsius, accelerated fatigue occurs. Sufficient breaks should
be taken during work and sports and direct sun should be avoided.
With a heat index between 30 and 40 degrees Celsius you can suffer from heat stroke, cramps and/or dehydration.
Physical exertion should be kept to a minimum, plenty of water should be drunk and sun should be avoided.
With a heat index between 40 and 55 degrees Celsius, the chance of heat stroke, cramping and/or dehydration
is even greater. Physical exertion should be avoided, plenty of water should be drunk and rest taken.
Try to stay in the shade as much as possible.
With a heat index of more than 55 degrees Celsius, there are very great dangers to public health.