Apparently, scientific experiment has proven that people who strip to their shorts outside in the winter don't get colds 'thataway'.
Why do we then cling to the old wives tale that one must "bundle up" against the cold weather?
Could it be that there is something to it? Does warmth fend off viral infection? If so, why?
The main concept to consider in this matter is the momentum of an object in a fluid which is changing direction. This is what is, at base, the core vector ingredient involved in viral transmission.
As an example, imagine a leaf floating on a stream along with a canoe with people in it. When the stream changes course, the leaf rapidly changes course with it but the canoe is thrown to the outside bank of the stream (tending to remain in rectilinear motion). The leaf would go straight also were it not for its very small mass which is easily pushed around by the much heavier water.
OK? Got it?
The clouds come overhead and stop the ultraviolet light from killing exposed viruses which are "hibernating" a few millimeters under the soil.
Under normal circumstances (a sunny day), the viruses which are constantly floating around in the air are few (because of the ultraviolet) and those that do make it into your throat are sucked in and simply blown back out harmlessly (just like a leaf on a stream that never hits the bank).
What about the warmth factor?Easy. A warm throat helps (significantly) to evaporate the minute water droplets that enter the nose or mouth. If the droplet is evaporated before it gets to the "curve" it is statistically more likely to be harmlessly "blown" back out.
What happens when someone sneezes in your face (who has a cold already)?
There is a way to test this hypothesis. Just have some volunteers go into a cold room "seeded" with virus droplets and have half strip to the waist and half keep warm with a coat and scarf. See if the exposed ones get colds more than the covered ones.
I just realized today that the biggest reason for getting all bundled up in cold weather is that you will get warmer and therefore won't breathe as much or as deeply. Because about 80% of the food we eat gets burned up just to maintain our body temperature ... the colder we are, the more that has to be burned to keep us at normal operating temperatures.
Consequently, if we are cold we must take in more air to burn the extra calories. When this happens we increase the probability that we will also take in a water droplet on which the offending virus is hitching a ride. Hence, in cold weather people put on hats, mittens, and scarves to cover the places of greatest heat loss. In merry old Victorian England this was the normal winter attire.