The air bites shrewdly, does it not? But sometimes that which seems to affect us most on these cheerless, dark November mornings is not so much the low temperature per se, but the penetrating dampness that pervades the chilling air, and which is blamed for the all the coughs and colds and bouts of rheumatism to which we imagine our nation to be unusually prone. We compare our lot unfavourably with the nice "dry cold" of Canada, perhaps, and other places like it.
But it is difficult to find physiological reasons why "dry" cold should be more tolerable than the same degree of coldness when the air is damp.
It is true that in a humid atmosphere clothing becomes wet and therefore less effective as an insulator, and that this may lead to heat loss and discomfort. Moreover, the pervasive winter dampness in an inadequately heating building is undoubtedly unpleasant. Nevertheless, for a person clothed to suit the circumstances, humid cold of itself is not more penetrating or enervating than dry cold, and in terms of the physics of heat transfer, the difference between the two is negligible. The argument that damp air conducts heat more rapidly from the body than dry air can be countered by the observation that dry air promotes more active cooling by evaporation.
It is probable that our preferences have very little to do with temperature or humidity at all. Dry cold is often accompanied by sunny skies, and this type of weather is not only psychologically more pleasing than overcast conditions, but the absorption of solar radiation adds to one's sense of comfort. You may well feel less unhappy in dry cold rather than humid cold, but it is probably not because of the difference in humidity.
Variations in the relative humidity, however, can be undeniably palpable in other ways. Human hair, for instance, becomes shorter when the air is very dry, but lengthens as humidity increases; those with a troublesome coiffure, if their hair is long and straight, may notice that dampness makes it limp, while naturally curly hair displays a tendency to frizz.
Those with arthritis or similar complaints may feel increased pain when there is a sudden change in the humidity. Also, scar tissue, corns and other abnormal skin have rates of expansion and contraction different to normal skin, so a sudden rise in the humidity may cause nerve endings to register a similar response.
And since rising humidity is often the precursor of approaching rain, so it is that Some by a painful elbow, hip or knee / Will shrewdly guess what weather's like to be.