Why isn't Y a vowel?

[pagey]

?

[CLOWN TICKLE]

It is where no other vowel fits, for example

my, why, hymn, lymph etc

[RATTER15]

Good question!! not sure if Clown Tickle has answered it by giving a few examples how Y is used, why don't we just include it as a vowel??

[heathfield]

Some grammarians do claim it to be a vowel. It's been a subject of discord amongst them for centuries.
The best answer is that it's both, as described here

[jno]

'vowels' and 'consonants' really describe sounds, not letters. The letter Y can perform both of these functions - vowel sound (ie no obstruction to the flow of breath) in the words clown tickle mentions; but a consonant sound in yes, year and so on. W can be a vowel in Welsh.

[Quizmonkey]

Precisely. Strictly speaking it's a semi-vocalic.

[vehelpfulguy]

Come to think of it, why do we separate letters out into vowels and consonants anyway ?

Does splitting them up serve any purpose ?

[joko]

mi, whi, himn, limph....sounds fine to me...

it can nearly always be substituted for an I

but not when it is a consonant form in yes, yellow etc

[alunrw]

it is a vowel in Welsh :-) as is W

[jenstar]

"Does splitting them up serve any purpose ?"

Um... it pads out "Countdown" a bit.