Humidity in Australia versus Humidity in Singapore ; a technical study on comfort.

The latent heat of vaporisation is the hidden heat which is taken from the environment to vaporise a liquid. For water, it is 22.5 kJoules per gram (22.5 kJ / g) of water when water is heated to 100 deg C. Hence 22.5 kJ is expended or 'lost' to the environment. The key point is that water evaporates at ALL temperatures to the environment and takes away heat from the surface where it was - hence the body which sweats and sweat evaporates, will feel cooler.

So during my trip to Canberra, I experienced temperatures of 25 deg C but with humidity of around 40% ; this means that the humidity in the air is 40% per cubic metre. The feeling even at 25 deg C is that while the sun is shining and the temperature is at 25 deg C, the dry air surrounding my body absorbs the sweat more quicker. Now when water evaporates, it does not necessarily need to evaporate at 100 deg C, so the sweat evaporates when my body is exercising or when it is hot (above 36.9 deg C) and hence sweat comes out through the pores.

Antibes Fishing Village Dec 2018 

Once there on my hands and legs, it will tend to evaporate fast and the heat lost by my body due to the latent heat of evaporation means my body gets cool.

Now I am sitting in my attic in my house writing this post, the temperature is also about 25 deg C, BUT the big difference is that the humidity in the air is a high 80% ; hence my body still operates well and sweat comes out. The big difference is that the sweat DOES NOT evaporate as fast due to the higher 80% humidity surroundings. Thus leaving the sweat on my arms and legs and with the salt content, I am sticky.

Pretty as a Picture, Antibes Village in Dec '18 wintertime 

Hence the feeling is an 'ugh' compared to an 'aaah' when I am in temperate countries like Australia or France.

That 'ugh' and 'aaah' feeling can and does contribute to our state of mind and sometimes tempers can blow when the body is uncomfortable in its environment. 

The solution, of course sit and play in an air conditioned environment and all will be solved.

Then, what about the environment outdoors ??? 

The late Lee Kwan Yew did once say that the most important invention of the 20th century (for the tropics anyway) was the air condition and the refrigeration system for chilling of food. 

Carpe Diem