How does wool keep us warm?

There are about 950 million sheep in the world, out of which more than 177.8 million sheep are in Australia alone. In winter, we all wear woollen clothes to protect our body from cold and also to keep our body warm. The wool we wear comes from the fleece of sheep. Good quality of wool comes from Merino sheep — a specially bred sheep that originally came from Spain. However, most wool is now produced in Australia. The largest sheep station in the world is the Commonwealth Hill in the north- west of South Australia. It grazes between 5,000 to 7,000 sheep. Do you know, how the woollen clothes keep our body warm? We know that the internal temperature of our body is 98.4°F but the skin temperature is about 91°F. We feel warm or cold only if a part of our body comes into contact with a body of different temperature. When the temperature of our surroundings is about 65°F we feel quite comfortable because the temperature of our body is about 25°F more than this temperature. In such a state, our body continuously radiates heat. If the temperature falls below it, we feel cold. Under this condition we wear clothes that are bad conductors of heat. Wool is a bad conductor of heat and its fibres can trap air in between themselves. Air is also a bad conductor of heat but, wool is more so and does not allow our body to radiate much heat. That is why we feel warm when we wear woollen clothes, which are also heavy. An important property of wool is that it can absorb moisture. About 1 kilogram of wool can absorb almost 120 grams of water vapour and despite this wool would appear dry. Due to this property wool can also absorb the sweat from the body, which provides warmth to the body. The absorption of moisture makes the wool slightly warm. Today, sheep are used mostly for wool and meat. Modern sheep have been specially bred to give the best combination of wool and meat.

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