Is it unlawful for a woman to raise the hair of her head to its middle and wear the headscarf over it?

Raising the hair of the head without exaggerating it with anything else is not forbidden. And the Prophet's (peace be upon him) saying: "Two types of people from the Fire I have not seen: women who are clothed yet naked, inclining [to evil] and causing [others] to incline; their heads are like the humps of leaning camels," refers to those who exaggerate their heads with some clothing or added hair until it becomes like a camel's hump, as mentioned by An-Nawawi.