If we will step outside without a coat on a snowy day then our blood vessels in the skin will become narrow and contract. It is a mechanism to conserve heat within our body in cold weather. If the blood vessels in the skin will become narrow and contract then less blood will flow in the blood vessels, this phenomenon is known as vasoconstriction. The blood of our body is warm but the exposure to the cold weather will cause the heat of the blood to dissipate into the environment. But constricted blood vessels will have less blood and hence heat loss is minimized which keeps the internal temperature of the body as normal even if outside environment is cold.
The hypothesis can be defined and a statement, which is a possible answer to a scientific question. The hypothesis is proposed on the basis of the researches and the tests, which are already performed. the hypothesis can be tested through different experimental processes and can be proved or disproved according to the results obtained by the experimentation.