Here's why:
* Short vowel sounds are typically found in words where the vowel is followed by a consonant. In "lemon", the "e" is followed by the consonant "m".
* Long vowel sounds are often found in words where the vowel is followed by a consonant and a silent "e" at the end of the word.
While the "e" in "lemon" is not silent, it is followed by a consonant, resulting in a short vowel sound.