Ever wonder why our arm hairs stand up?

So, we have all noticed that when we are cold the hair on our arms stand up right? This isn't magic guys! As you have already probably guessed, it has a scientific explanation!

The hairs on our skin trap more air if they are standing up, and of course less if they are lying flat. So then can you figure out why they stand up when its cold and why they lay flat when it's hot?

In colder weather the hairs stand up, because the hair muscles contract, to trap a thicker layer of air. So it cuts down even more on heat loss.

In hot weather the hairs lie flat, because the hair muscles are now relaxing, so less air is trapped close to the skin. So more heat is lost by radiation.