[Grammar] The Definite Article with the word ‘hair’

[northpath]

There are two sentences in the British textbook ‘Spotlight’ by Virginia Evans, Jenny Dooley and others:
“Emma has a pretty face with straight blond hair.”
“Adam is the young boy with THE spiky blond hair.”
Why is the definite article used in the second sentence?

 

[SoothingDave]

There are lots of people with straight blond hair. The boy who has the spiky blond hair is unique, which is why a definite article is used.

 

[Rover_KE]

What do the authors of the textbook have to say about the difference?

 

[northpath]

No difference is stressed; these are just two of several examples of using the word ‘hair’. Except the sentence two, no article was used in other sentences.

 

[Roman55]

If the indefinite article had been used before 'young boy' then the definite article would not have been used before 'spiky hair'.

Adam is a young boy with spiky blond hair.

By saying the young boy he is being pointed out, and identified as the one with the spiky blond hair.