High Humidity by Geoff Young

Temperatures in August started where July ended. High temperatures across most parts of Spain both day and night. In the August edition of the Gran Alacant Advertiser, Gabriela wrote an excellent article about Physical Exercise and Heat, offering well timed advice on dealing with the heat.

However, as well as the high temperatures, we have experienced high levels of humidity in the air, sometimes as much as 80%.

But why does humidity make us feel so uncomfortable? Firstly, a little bit of science. Absolute Humidity is the mass of water vapour divided by the mass of dry air in a volume of air at a given temperature. In other words, the hotter the air is, the more water it contains. Relative humidity is the ratio of current absolute humidity to the highest possible absolute humidity. A reading of 100% relative humidity means the air is fully saturated with water vapour.

As Gabriela wrote, when the body’s core temperature rises, there is a physiological reponse to reduce the temperature. Skin pores open to allow droplets of perspiration to cover the skin with a layer of water which will reduce skin temperature when it evaporates. However, when the humidity levels are high and the air already contains high levels of moisture the perspiration wont evaporate into the air. We start to feel uncomfortable when the humidity is approximately 45%. As a result of the humdity we feel a lot hotter than the actual temperature. For example With 100% humidity air temperature of 75 Deg F will feel like 80 deg F.

Keep safe, try and avoid the direct sun and keep hydrated by drinking plenty of water.