I Feel Warmer in My Winter Coat

Imagine two people, Person A and Person B. Person A is walking to his car on a winter afternoon wearing a t-shirt and jeans. Person B is also walking to his car on a winter afternoon wearing a t-shirt and jeans. However, Person B is wearing a winter coat. Which man is warmer? If you were to ask 100 people, some would say A, some would say B, and some would just come clean and say they didn't know. The answer, and this may surprise the powers that be, is that Person B, the man with the winter coat, is warmer.
How can I say this which such certainty? I am the man in both scenarios. I am Person A and Person B!!! About three weeks ago, I went outside to grab something out of my car, which was parked out on the street. I had a grey t-shirt and blue jeans on but no coat. I was really cold. I grabbed what I needed and hurried back inside. No more than a half hour later, it was time for me to head to school for class. This time I grabbed my winter coat on my way out and put it on. I was much warmer this time. I'm no scientist, but the coat must have been the reason.
Look I'm not trying to shock anybody here, and if you want to keep living your life, eating Frosted Flakes and driving your Dodge Stratus, feel free to ignore my posts. Stay in your little bubble if you must. I just want to pass on what I've learned, and I really do feel warmer in my winter coat.