Why will a string vest with a shirt over it keep you as warm as a jumper?

Answer

I assume you're from the UK and "jumper" is what Americans call a "sweater," and "string vest" is a "knit undershirt."

DuPont and other manufacturers would have you believe that their materials make great insulators, but in fact they are merely containers for one of the lightest and best insulators of all: air. Air is such a great insulator that you can hold your fingers within millimeters of flames and red-hot pokers. Try that with an aluminum rod: even the "cool" end will be too hot to touch.

Air does get warm, and as warm air rises, it gets replaced by cool air. The warm air carries heat around. The trick is to get the air to sit still, so it can't carry the heat away. Insulators trap air and stop it from moving around.

A jumper/sweater has a lot of bulk and traps air not only between the yarn, but between the fibers of the yarn itself. The air can blow away, but if there's enough thickness, at least some air will stay put. A string vest (undershirt) holds air in the gaps between its threads as well, but since it's thin and a very open weave, the air tends to move away quickly in a breeze. The addition of a shirt helps keep the air close and produce the same effect as a sweater/jumper. You can improve the insulating value of any knit garment by adding an outer windbreak layer to keep the air close.

This answer is closed to changes. This is done in rare cases when questions are being vandalized or answers have become debates. Email WikiAnswers @ Answers.com if you would like it to be reopened.

First answer by Eric. Last edit by Eric. Question popularity: 125 [recommend question]

Research your answer:

Can you answer other questions about science?

Answers.com > Wiki Answers > Categories > Science > Why will a string vest with a shirt over it keep you as warm as a jumper?

Our contributors said this page should be displayed for the questions below. (Where do these come from

)

If any of these are not a genuine rephrasing of the question, please help out and edit these alternates.

How can a stirng vest keep you warm? Why does a string vest keep you warm? Why is a string vest a good insulator? How does a wooly jumper keep you warm? How does a woolly jumper keep you warm? Why is a string vest such a good insulator? Why do people feel cold in a string vest but warmer when they put a tight t-shirt over it? Why does someone feel cold in a string vest but warm if they wear a tight shirt over it?