"Rub your chest. Your hands and legs can take care of themselves".- Henri Ducard to Bruce Wayne (aka Batman) in "The Batman Begins".
Have you ever thought about it?
Actually there is no rocket science behind it. It is well-known that the body mechanism works in priority basis. The reason you feel cold in your legs and hands on a winter day is because you haven't protected your upper body well from the cold weather. Two of the most important organs in the body are your heart and your kidneys. When they are not well protected, the body pulls in blood from your legs and hands to give it to your heart, kidney and other important organs in your upper body. As your hands and legs are low on blood, they feel cold.
So, how to wear shorts on a cold winter day?
Option 1: You can wear your usual clothes on your upper body and rub your chest the way Batman did.
Option 2: You can wear adequate number of warm clothes on your upper body.
If your upper body is warm enough, you can wear shorts. No probs.
Why do you shiver in cold? The reason is somewhat similar to the one you just read. If you still can't figure it out, stay tuned for my next post.
[pseudoscience: the information I write with the 'pseudoscience' title may or may not be correct. I simply write what I think and what I guess. The sole purpose I have is to analyze scientific issues in the simplest way possible. Trusting them is upon you.]