Extract from Wikipedia (http://en.wikipedia.org/wiki/Vowel_length#Long_vowels_in_English)

Traditionally, the vowels /eɪ iː aɪ oʊ juː/ (as in bait beet bite boat beauty) are said to be the "long" counterparts of the vowels /æ ɛ ɪ ɒ ʌ/ (as in bat bet bit bot but) which are said to be "short". Some websites (such as http://vocabulary.com and http://dictionary.com ) provide pronunciation of these words.